Four youths attacked and robbed a 37-year-old man with cerebral palsy as he walked to work in a Lancashire town.
Police said the victim, who is also partially deaf, was surrounded by the gang on a cycle track in Accrington in the early hours of Tuesday.
He was punched to the ground and then repeatedly kicked by the offenders, who stole his MP3 player.
Det Con Mark Cruise, of Lancashire Police, said the "cowardly" attackers had targeted a vulnerable man.
He said: "These offenders have preyed on a man who was unable to fight back and he was left with cuts and bruises and was extremely distressed by the ordeal.
"I would urge anyone with information on this cowardly attack to come forward."
He added that the victim's hearing aid had been destroyed in the robbery, which happened on the cycle track between Mount Street and Manchester Road between 0600 GMT and 0630 GMT.
Police believe the attack could be linked to an incident in which a cyclist was pushed off his bike on Marsden Street, Accrington, shortly afterwards.