Arnold Chan says in a website post that he found out earlier this month he has nasopharyngeal cancer.
The disease affects the part of the throat that lies behind the nose.
He says he will have to undergo a period of aggressive treatment, but his doctors say his prognosis is excellent.
Chan says he'll have to spend some time away from Parliament, and his office will help handle his constituency work in his absence.
The former Queen's Park staffer and lawyer won the Scarborough-Agincourt seat vacated by longtime Liberal Jim Karygiannis.