Chester Spinek, 87, was driving a 1996 Saturn south on Route 110 near Nathalie Avenue about 8:45 p.m. when he tried to make a left turn, police said.
Spinek's car hit a 2005 Acura TL that was traveling north on Route 110, police said.
Suffolk County detectives are investigating the crash.
Both vehicles were impounded for safety checks, police said.
Anyone with information on the crash can call the First Squad at 631-854-8152. All calls will be kept confidential.