She was apparently attacked by a man who had attempted to dance with her. Sources say she blew him off and walked away, and he followed her into the 3rd-floor bathroom area.
Police say the victim was in the ladies room bathroom stall when the suspect kicked the door open and attacked.
The woman was unconscious when she was discovered by a girlfriend, who became concerned after the victim didn't return from the bathroom.
"Her friend goes up to find her, she was missing for a period of time," NYPD Commissioner Ray Kelly said. "She goes up, finds her sprawled on the floor."
Investigators say the friend called an ambulance, but did not call police. Neither did anyone from the bar.
The bar manager declined to comment to Eyewitness News.
The woman was rushed to New York Presbyterian Hospital, where she was taken to surgery. The injuries she sustained are reportedly consistent with her head hitting the toilet.
"She apparently becomes conscious about 5:30 in the morning, tells what happens, and that's when the police respond," Kelly said.
Investigators released two surveillance videos of the suspect hoping someone might recognize him.