A 51-year-old straphanger had his neck slashed during an argument on a Harlem subway platform Monday morning, cops said.

The violent incident unfolded around 6 a.m. while the man was waiting for the subway at West 125th Street and Lenox Avenue, according to police.

He got into some kind of dispute with another man, who cut him, cops said. It was not immediately known if the pair knew each other or what the fight was over.

EMS rushed the victim to Harlem Hospital, where he was in critical condition.

His attacker fled after the encounter.