Police believe the woman is another victim of the "knockout game".
The woman was walking along Wortman Avenue in East New York around 11:30 when the suspect allegedly approached her from behind, and struck her on the head, causing her to fall on the ground. The suspect then fled the scene.
The victim was taken to Brookdale Hospital, where she was treated and released for a head injury.
Friday's victim joins a growing and alarming list of other victims of the knockout game, where the goal is to walk up to unsuspecting strangers and knock them out with a single punch.
"This is what we're coming to in our community that our children are finding recreation in hurting someone," said Lesha Seku of the National Action Network in Harlem. In Bushwick recently, a 63-year-old man was sucker-punched, as was another man in Crown Heights.
Anyone with information in regards to this incident is asked to call the NYPD's Crime Stoppers Hotline at 800-577-TIPS.