Detectives from Transit Crime Investigation Unit are investigating an assault which occurred in Sunshine last month.
Investigators have been told the victim and his friend attended the Sunshine Railway Station about 3.15pm on Thursday 12 September.
As they moved along the platform the victim noticed a group of men were taunting his friend.
The situation escalated and the 35-year-old man from Western Australia was assaulted by the four men.
The offenders then left the area.
Officers have released images of four men that they believe may be able to assist with their enquires.
Anyone who recognises the men or with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au
Senior Constable Adam West