He was a surgeon at Hôtel-Dieu de Paris, and a favored student of Ambroise Paré (1510–1590), who was also his father-in-law.
In 1584 Guillemeau published Traité des maladies de l'oeil ("Treatise on eye diseases"), considered one of the best Renaissance-era works in ophthalmic medicine.
[1] He is also credited for providing the first description involving repair of palpebral coloboma, an eyelid defect he referred to as paupieres accurcies.
Guillemeau was a practitioner of the podalic version for use in cases of placenta praevia, a procedure earlier revived by Ambroise Paré.
Other publications by Guillemeau include Tables anatomiques and La chirurgie française.