Police are appealing for public assistance to help locate missing man Peter Clark.
The 65-year-old was last seen during a group motorcycle ride about 11.30am on Wednesday in Daylesford.
Mr Clark was riding a 2005 grey BMW K1200s with registration EK698.
He was last seen wearing a black jacket, black jeans and a silver motorcycle helmet.
Police and family have concerns for his welfare as it is out of character for him not to make contact.
Police have released an image of Peter and a photo of a motorbike similar to his in the hope someone can provide information regarding his current whereabouts.
Anyone who sees Mr Clark is urged to contact Moonee Ponds Police Station on 9373 5200.