The fire erupted about 11 a.m. in a room on the 10th floor of the hospital at 506 Lenox Ave., near West 135th Street, an FDNY spokesman said.
Firefighters brought the blaze under control about 47 minutes later, officials said.
There were no reported injuries.
It wasn't immediately clear how the fire was ignited.
Hospital officials referred questions about the fire to their 11:59 a.m. tweet that said patients on the floor were removed to a safe location.