In 1865 he earned his medical degree, and afterwards served as director of a pathological anatomy laboratory in Clamart (1868–1878). From 1885 until his death in 1907 he was director of Hôpital des Enfants Malades in Paris. Also, he was a member of the board of directors at the Pasteur Institute.
Grancher is remembered for his research of tuberculosis. He was a pioneer in the creation of safeguards for the prevention of childhood tuberculosis, and was an advocate of isolation and antisepsis in the fight against the disease. In 1897 with Jules Comby (1853–1947) and Antoine Marfan (1858–1942), he published Traité des maladies de l’enfance (Treatise of the Diseases of Childhood).
In 1885, Grancher and Alfred Vulpian (1826–1887) were instrumental in convincing Louis Pasteur (1822–1895) to perform the first successful vaccination against rabies on Joseph Meister, a 9-year-old boy who had been mauled by a rabid dog. In 1887 at the request of Pasteur, Grancher defended the rabies vaccination to the Académie de Médecine, citing its successful survival rate.
- Portail Institut Pasteur (chronological biography)