The NYPD released a photo of the suspect.
Investigators say the woman has been stealing wallets and credit cards from the women's locker room at the Bedford-Stuyvesant YMCA.
She allegedly struck six times between June 13 and July 22.
The suspect is described as a white female with tattoos on her left arm, from her shoulder to her elbow.
Anyone with information is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).