Fallopius served as canon of the cathedral of Modena and then turned to the study of medicine (medicine, history of) at the University of Ferrara, where he became a teacher of anatomy. He then held positions at the University of Pisa (1548–51) and at Padua (1551–62). His exhaustive observations, made during dissection of human cadavers and outlined in Observationes anatomicae (1561), earned him the respect and admiration of his colleagues, including the great Renaissance anatomist Andreas Vesalius.

Fallopius discovered the tubes that connect the ovaries to the uterus (now known as fallopian tubes (fallopian tube)) and several major nerves of the head and face. He described the semicircular canals of the inner ear (responsible for maintaining body equilibrium) and named the vagina, placenta, clitoris, palate, and cochlea (the snail-shaped organ of hearing in the inner ear). A friend and supporter of Vesalius, he joined him in a vigorous assault on the principles of the classic Greek anatomist Galen, which resulted in a shift of attitude essential to the development of Renaissance medicine.