Race Director Bill Burke says in a statement that the 64-year-old man died in Sunday's race.
He didn't say how he died.
A 40-year-old woman was treated on the scene, then taken to a hospital.
Burke says the thoughts and prayers of the triathlon community are with the athletes and their families.
Participants in the yearly race swim 1.5 kilometers in the Hudson River, bike 40 kilometers and run 10 kilometers.