A major search involving police aircraft and SES personnel is underway for an elderly man with dementia who was last seen going for a walk in a small Wheatbelt town on Saturday morning.

Wagin Police are requesting assistance from the public to help locate 87-year-old James Ballantyne.

Mr Ballantyne was last seen going to for a walk around Leonara Street in Wagin about 10.30am on Saturday.

Police said Mr Ballantyne lives with dementia and there are fears he will be unable to find his way home.

Wagin residents are asked to check their backyards, sheds and vehicles in case Mr Ballantyne sought shelter overnight.

Mr Ballantyne is described as being 183cm tall, of medium build and with short greying hair.

He was last seen wearing a navy-blue jumper and khaki-tan pants.

Wagin Police are being assisted by WA Police Air Wing assets and drone operators with their search. SES personnel have also joined search efforts.

Anyone who sights James or who has information about his location is urged to contact police immediately on 131 444.