The Matilda effect is the systematic repression and denial of the contribution of women scientists in research, whose work is often attributed to their male colleagues. This effect was first described in 1993 by science historian Margaret W. Rossiter.
It is named after the U.S. women's rights activist Matilda Joslyn Gage, who first observed this phenomenon at the end of the 19th century. The Matilda effect is related to the Matthew effect, which states that eminent scientists will often get more credit than a comparatively unknown researcher, even if their work is similar.
Rossiter provides several examples of this effect: Trotula, an Italian physician (11th–12th centuries), wrote books which were attributed to male authors after her death, and hostility towards women as teachers and healers led to her very existence being denied. Known cases of the effect from the 20th century include among others Rosalind Franklin, Lise Meitner, Marietta Blau and Jocelyn Bell Burnell.
From an analysis of more than a thousand research publications from the years 1991-2005, it was shown that male scientists more often cite the publications of male authors than of female authors. In 2012, two female researchers from Radboud University Nijmegen showed that in the Netherlands the sex of professorship candidates influences the evaluation made of them. Similar cases are described in an Italian study  corroborated further by American and Spanish studies  .
Swiss researchers have indicated that mass media ask male scientists more often to contribute on shows than they do their female fellow scientists.
USA male scientists still receive much more recognition and awards compared with women scientists, despite similar achievements. This difference is, fortunately, diminishing. It was more pronounced in the nineteen-nineties than in the 2000s.
Famous examples of women in history of science include:
- Trotula - Italian medic of the living 11th - 12th century, author of works that after her death started to be published and ascribed to male authors. To further support male authorship, her very existence was questioned.
- Rosalind Franklin - now recognized as one of the main contributors to the discovery of DNA structure. At the time of the discovery by Francis Crick and James Dewey Watson her work was not properly given credit.
- Gerty Cori - worked for years as her husband's assistant despite having equal qualification as him for professor position.
- Mary Whiton Calkins - Harvard University refused to give her PhD title, even though she fulfilled all conditions to receive one.
- Marthe Gautier - recently revealed example of Matilda effect. Gautier is now recognized for her important role in the discovery of the Down syndrome while it has been attributed exclusively to Jérôme Lejeune.
- Programmers of ENIAC - several women made substantial contributions to the project, including Adele Goldstine, Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman, but histories of ENIAC have typically not addressed these contributions, and have at times focused on hardware accomplishments rather than software accomplishments. More information can be found in Jennifer S. Light's essay, "When Computers Were Women",  and in a 2014 documentary on the ENIAC programmers project.
Examples of male scientists favoured over female scientists by Nobel Prize:
- In 1934, the Nobel Prize in physiology or medicine was awarded to George Whipple, George Richards Minot and William P. Murphy. They felt their female coworker Frieda Robscheit-Robbins was excluded on grounds of her sex and shared the prize with her. She was co-author of almost all publications by Whipple.
- In 1944, the Nobel Prize in Physics was given to Otto Hahn as sole recipient. Lise Meitner, who laid the theoretical foundations for nuclear fission, explained Hahn's observations, and coined the term 'nuclear fission', was not recognized by the Nobel Committee.
- In 1950, Cecil Powell received Nobel Prize in Physics for his development of the photographic method of studying nuclear processes and for the resulting discovery of the pion (pi-meson). Marietta Blau did pioneering work in this field but Erwin Schrödinger did not nominate her for the prize.
- In 1956, two American physicists Tsung-Dao Lee and Chen Ning Yang, predicted the violation of the parity law in weak interactions and suggested a possible experiment to verify it. In 1957, Chien-Shiung Wu performed the necessary experiment in collaboration with National Institute of Standards and Technology and showed the parity violation in the case of beta decay. The Nobel Prize in Physics in 1957 was awarded to the male physicists and Wu was omitted. She received the Wolf Prize in 1987 in recognition for her work.
- In 1974 Jocelyn Bell Burnell discovered the first radio pulsars. For this discovery the Nobel Prize was awarded to her supervisor Antony Hewish and Martin Ryle, citing Ryle and Hewish for their pioneering work in radio-astrophysics, with particular mention of Ryle's work on aperture-synthesis technique, and Hewish's decisive role in the discovery of pulsars. Burnell was left out. Being a PhD student at the time of the discovery she felt the intellectual effort was done mostly by her supervisor but her omission was disproved by several prominent astronomers including Sir Fred Hoyle. Dr. Iosif Shklovsky, recipient of the 1972 Bruce Medal, had sought out Bell at the 1970 International Astronomical Union's General Assembly, to tell her: "Miss Bell, you have made the greatest astronomical discovery of the twentieth century."
Ben Barres, who is a neurobiologist at Stanford and has transitioned from female to male, has talked about his experiences of his scientific achievements being perceived differently depending on gender. 
- Rossiter Margaret W. (1993), "The Matthew/Matilda Effect in Science", Social Studies of Science (London: Sage Publ.) 23: 325–341, ISSN 0306-3127
- Silvia Knobloch-Westerwick; Carroll J. Glynn (2013), "The Matilda Effect—Role Congruity Effects on Scholarly Communication A Citation Analysis of Communication Research and Journal of Communication Articles", Communication Research (Sage Publ.), 40 (1): 3–26, doi:10.1177/0093650211418339
- Marieke van den Brink; Yvonne Benschop, "Gender practices in the construction of academic excellence: Sheep with five legs", Organization, 19 (4): 507–524, doi:10.1177/1350508411414293
- Andrea Cerroni; Zenia Simonella, "Ethos and symbolic violence among women of science: An empirical study", Social Science Information, 51 (2): 165–182, doi:10.1177/0539018412437102
- Peter Hegarty; Zoe Walton, "The Consequences of Predicting Scientific Impact in Psychology Using Journal Impact Factors", Perspectives on Psychological Science, 7 (1): 72–78, doi:10.1177/1745691611429356
- María Luisa Jiménez-Rodrigo1; Emilia Martínez-Morante; María del Mar García-Calvente; Carlos Álvarez-Dardet (2008), "Through gender parity in scientific publications", Journal of Epidemiology & Community Health, doi:10.1136/jech.2008.074294
- Fabienne Crettaz von Roten (2011), "Gender Differences in Scientists’ Public Outreach and Engagement Activities", Science Communication, 33 (1): 52–75, doi:10.1177/1075547010378658
- Anne E. Lincoln; Stephanie Pincus; Janet Bandows Koster; Phoebe S. Leboy (2012), "The Matilda Effect in science: Awards and prizes in the US, 1990s and 2000s", Social Studies of Science, 42 (2): 307–320, doi:10.1177/0306312711435830
- Light, Jennifer S. (1999). "When Computers Were Women". Technology and Culture 40 (3): 455–483.
- Shankar Vedantam, (13 July 2006). Male Scientist Writes of Life as Female Scientist: Biologist Who Underwent Sex Change Describes Biases Against Women. Washington Post