Origins and Calling
By the synaxarion accounts, Thallelaios came from Lebanon in Phoenicia, a region within the wider province of Syria. His father, named Beroukias (Berucius), is described as a military commander, and his mother as Romylia (Romila); he is also said to have had a brother who served as a subdeacon. The sources place him in his eighteenth year at the time of his death.
He is recorded to have studied medicine under a physician named Makarios. Because he gave his medical care to the sick without seeking payment, the tradition counts him among the Unmercenary physicians, the rank under which he is venerated.