A man was found in an alleyway after being assaulted and suffering head and spinal injuries.
The male victim, 25, was found off Huddersfield Road, Ravensthorpe, at around 11.04pm on Saturday evening.
His injuries are not thought to be serious.
Police believe three men may have been responsible for the attack, which they think happened between 10.20pm and 10.57pm.
Officers also cordoned off the area at 1.04pm the next day to investigate.
The victim was taken to Dewsbury and District Hospital on the night of the attack but released the morning after.
If anybody has information contact PC2578 Bradley of Dewsbury CID on 101.