Abu Sahl 'Isa ibn Yahya al-Masihi al-Jurjani () was a Persian Christian physician, from Gorgan, east of the Caspian Sea, in Iran.
He was the teacher of Avicenna. He wrote an encyclopedic treatise on medicine of one hundred chapters (al-mā'a fi-l-sanā'a al-tabi'iyyah; ), which is one of the earliest Arabic works of its kind and may have been in some respects the model of Avicenna's Qanun.
He wrote other treatises on measles, on the plague, on the pulse, etc.