Camillus entered the Capuchin novitiate three times, but a nagging leg injury that he received while fighting the Turks, forced him to give up each time. He went to Rome for medical treatment where he met Saint Philip Neri who became his priest and confessor. He moved into San Giacomo Hospital for the incurable, and eventually became its administrator. Lacking an education, he began to study with children when he was 32 years old.
Camillus tried to found a lay order of hospital caregivers but failed. He decided to become a priest and was ordained in 1582. In 1584, Camillus founded the Congregation of the Servants of the Sick (the Camellians) who care for the sick in both hospitals and homes. It was approved by Pope Sixtus V in 1586 and erected into an order by Pope Gregory XIV in 1591. The order expanded with houses in several countries, and today it maintains a website, http://www.camillians.org/. Camillus honored the sick as living images of Christ, and hoped that the service he gave them did penance for his wayward youth. Camillus was reported to have the gifts of miraculous healing and prophecy.
Saint Camillus of Lellis died of natural causes on July 14, 1614 at Genoa, Italy. His relics are in the Church of Saint Mary Magdalen at Rome.