A 20-year-old woman was assaulted as she left Rubix nightclub in Corby town centre on Sunday (October 12).
The victim was leaving the club in Corporation Street with friends between 1.30am and 2.30am when she was attacked by a young woman.
She needed hospital treatment for her injuries.
The offender was a white woman, aged about 23, of average build with dark, shoulder length hair.
Witnesses or anyone with information about the incident are asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.