This Saint, who had Nicomedia as his homeland, was the son of Eustorgius and Eubula. His father was an idolater, but his mother was a Christian from her ancestors. It was through her that he was instructed in piety, and still later, he was catechized in the Faith of Christ by Saint Hermolaus (see July 26) and baptized by him. Being proficient in the physician's vocation, he practiced it in a philanthropic manner, healing every illness more by the grace of Christ than by medicines. Thus, although his parents had named him Pantoleon ("in all things a lion"), because of the compassion he showed for the souls and bodies of all, he was worthily renamed Panteleimon, meaning "all-merciful."

On one occasion, when he restored the sight of a certain blind man by calling on the Divine Name, he enlightened also the eyes of this man's soul to the knowledge of the truth. This also became the cause for the martyrdom of him who had been blind, since when he was asked by whom and in what manner his eyes had been opened, in imitation of that blind man of the Gospel he confessed with boldness both who the physician was and the manner of his healing. For this he was put to death immediately. Panteleimon was arrested also, and having endured many wounds, he was finally beheaded in the year 305, during the reign of Maximian.

Saint Panteleimon is one of the Holy Unmercenaries, and is held in special honor among them, even as Saint George is among the Martyrs.