Nothing is known of their lives except that they suffered martyrdom in Syria during the persecution of the Emperor Diocletian.
A church erected on the site of their burial place was enlarged by the emperor Justinian. Devotion to the two saints spread rapidly in both East and West. A famous basilica was erected in their honor in Constantinople. Their names were placed in the canon of the Mass (Eucharistic Prayer I) , probably in the sixth century.
Legend says that they were twin brothers born in Arabia, who became skilled doctors. They were among those who are venerated in the East as the "moneyless ones" because they did not charge a fee for their services. It was impossible that such prominent persons would escape unnoticed in time of persecution: They were arrested and beheaded.
Nine centuries later, Francis of Assisi (October 4) rebuilt the dilapidated San Damiano chapel outside Assisi.
In the Preface for Martyrs I, the Church acknowledges that a martyr's blood shows God "marvelous works, by which in our weakness you perfect your powerand on the feeble bestow power to bear you witness, through Christ our Lord."