- Not to be confused with a biometric passport.
An athlete biological passport is an individual, electronic record for professional athletes, in which profiles of biological markers of doping and results of doping tests are collated over a period of time. Doping violations can be detected by noting variances from an athlete’s established levels outside permissible limits, rather than testing for and identifying illegal substances.
Although the terminology athlete passport is recent, the use of biological markers of doping has a long history in anti-doping. Maybe the first marker of doping, that tries to detect a prohibited substance not based on its presence in urine or blood, but through the induced deviations in biological parameters, is the so-called testosterone over epitestosterone ratio (T/E). The T/E has been used by sports authorities since the beginning of the 1980s to detect anabolic steroids in urine samples. A decade later, in 1997, markers of blood doping were introduced by some international federations, such as the Union Cycliste Internationale and the Federation Internationale de Ski, to deter the abuse of recombinant erythropoietin that was undetectable by direct means at that time. It is only in 2002 that the paradigm to use biological markers of doping took the terminology 'athlete passport. The merits of this testing paradigm were exposed in the scientific literature  and the terminology adopted by the World Anti-Doping agency.
Many believe[who?] that the athlete passport provides an excellent alternative to ensure fairness in elite sports. While a new drug test must be developed and validated for each new drug, the main advantage of the athlete passport is that it is based on the stability of the physiology of the human being. New drugs are produced at an unprecedented pace today and there is often a lag of several years between the availability of a new drug and the application of an effective detection method. On the contrary, the physiology of the human being remains the same through several generations and all biomarkers developed today in the athlete passport will remain valid for at least several decades. For example, the blood module of the passport is already sensitive today to any new future form of recombinant erythropoietin, as well as to any form of gene doping that will enhance oxygen transfer to the muscles. Also, while a negative drug test does not necessarily mean that the athlete did not dope, the athlete can present his/her passport at the beginning of a competition to attest that he/she will compete in his/her natural, unaltered condition.
The athlete passport has received a lot of attention when its blood module was established at the beginning of the 2008 racing season by the Union Cycliste Internationale. In May 2008 the UCI revealed that 23 riders were under suspicion of doping following the first phase of blood tests conducted under the new biological passport. In 2010, the athlete's passport took a new meaning when designer drugs such as recombinant erythropoietin and anabolic steroids having the same molecular structure as those naturally produced by the body became available.
The blood module of the athlete passport aims to detect any form of blood doping, the steroid module any form of doping with anabolic steroid and the endocrine module any modification of the growth hormone/IGF-1 axis. Each of these modules are however at different steps of development, validation and application in sports.
Cyclists sanctioned on the basis of their biological passport 
The biological passport programme has allowed the Union Cycliste Internationale to sanction riders for committing an anti-doping rule violation. Riders have also been targeted with further doping controls based on their biological passport.
- Igor Astarloa received a two-year sanction as a result of abnormalities detected in his biological passport.
- Pietro Caucchioli received a two-year sanction as a result of abnormalities detected in his biological passport.
- Antonio Colom tested positive for EPO in an out-of-competition control in April 2009, after having been targeted under the biological passport programme. He received a two-year sanction.
- Francesco De Bonis received a two-year sanction as a result of abnormalities detected in his biological passport.
- Thomas Dekker tested positive for EPO in a retroactive test carried out on a urine sample taken in December 2007. Dekker's hematological profile led the UCI to review the EPO analyses for urine samples conducted since the introduction of the biological passport programme.
- Franco Pellizotti received a two-year sanction as a result of abnormalities detected in his biological passport.
- Ricardo Serrano received a two-year sanction after being caught under the UCI's biological passport programme. Evidence against Serrano was based on an abnormal haematological profile and two laboratory reports indicating the detection of CERA in two of his blood samples.
- Tadej Valjavec received a two-year sanction as a result of abnormalities detected in his biological passport.
- Swiss Laboratory for Doping Analyses. "Information on the athlete biological passport".
- Ashenden M. (March 2002). "A strategy to detect doping in sports". Haematologica (Haematologica) 87 (3): 225–32. PMID 11869930.
- "Q-A on the athlete passport". World Anti-Doping Agency.
- "Implementation of blood passport by UCI". UCI.
- Richard Moore (2008-05-03). "Blood tests cast doubt on 23 riders". The Guardian.
- "Glycosylation-modified erythropoietin". Int. J. Hematol. 91 (2): 238–44. March 2010. doi:10.1007/s12185-010-0496-x. PMID 20131103.
- "CAS upholds biological passport, slaps Pellizotti and Caucchioli with 2-year bans". VeloNews. 8 March 2011.
- "Biological Passport: Antonio Colom sanctioned for two years, given large fine". Velonation.com. 27 May 2010.
- Shane Stokes (22 June 2011). "CAS dismisses doping ban appeal by De Bonis over biological passport". Velonation.com.
- Susan Westemeyer (1 July 2009). "Dekker caught under biological passport programme". cyclingnews.com.
- "Biological Passport: Ricardo Serrano given two-year suspension by RFEC for EPO use". Velonation.com. 17 June 2010.
- "'Biological passport' pays off as Tadej Valjavec receives two-year ban". The Guardian. 22 April 2011.