Police say 72-year old John Bertuzzi of Middle Island was killed in the crash.
He was driving one of the cars that collided on North Ocean Avenue in North Patchogue about 5:30 p.m. Saturday.
One vehicle came to rest in the carport of a nearby home.
A woman and man who were in the other car are in serious condition.
Their 13-month old son only suffered minor injuries, and was treated and released.