A man was knocked to the floor and then stamped on as he lay on the floor in an assault in Borehamwood on Friday afternoon.
Police were called to reports of a serious attack outside Lloyds bank, in Shenley Road shortly before 3.30pm.
The victim was punched several times and then fell to the ground as a result of the blows.
He was then stamped on before his attacker walked off.
The 22-year-old man from Borehamwood suffered serious cuts and bruising to his face and was taken to hospital in London for treatment.
The attacker was described as a white man aged in his early 20s, with short cropped hair and was wearing a white t-shirt, faded blue jeans and trainers.
Detective Constable Rob Fleming, from the Hertsmere Local Crime Unit, said: “This was a serious assault that left the victim concussed and needing surgery for the injuries he has suffered to his face. I’m keen to speak to anyone who can help me establish the circumstances around the incident or who the offender is.”
Anyone with information about the incident should contact police on the non-emergency number 101.