A dispute in the mezzanine at the 175th Street A train station in Washington Heights just before 6 p.m. led to the violence, according to police.
When officers arrived they found the victim with with multiple stab wounds.
He was taken to the hospital where he was pronounced dead.
The victim was later identified as Johnny Medina of Manhattan.
The reason for the dispute remains under investigation.
There are no arrests.
"This was a senseless attack that spilled from the street to the subway, and we are providing full cooperation in the investigation, with confidence the NYPD will rapidly identify and apprehend the perpetrator," MTA Communications Director Tim Minton said in a statement.
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