A woman was walking down Kettering Road in Northampton, towards the town centre, when a man who was stood in a doorway pulled down his trousers and exposed himself to the victim.
The incident happened between Hood Street and Cowper Street at around 10.35am on Friday, 17 March.
The offender is described as Middle Eastern, between 30 – 50 years of age and around 5ft 9ins tall. He was of medium build, with black, greasy, curly hair down to his ears. He was unshaven and wearing a black t-shirt and grey jogging bottoms.
Anyone with information can contact Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.