A man required stitches after being hit on the head from behind in what police say was an unprovoked attack in Yeovil.
The 20-year-old was approached by an unknown man whilst walking on Sparrow Road in the early hours of 5 September.
He was then hit on the head with what is thought to have been a roof tile or a scaffolding pole.
Two women who were with the 20-year-old chased the attacker after he tried to continue the assault, and he made off along Mudford Road.
The victim needed 10 stitches to his head at Yeovil District Hospital.
The offender is described as white, with brown hair and wearing a grey t-shirt.
Police are appealing for witnesses.