Officers are conducting inquiries and appealing for the assistance of the public in tracing a 75 year-old man.
Robin Green is reported missing from the West End area of Aberdeen.
He was last seen at around 10am on Thursday at Craigton Park in the city.
Mr Green is described as white, around 5ft 11ins in height and of slight build with grey-coloured hair.
Sergeant Elizabeth Irvine from North East Division said: “We are becoming increasingly concerned for Robin’s welfare and safety and we are anxious to trace him safe and well.
“He is known to frequent the Deeside area, from Banchory to Braemar, extending to the Glenshee area, where he engages in hill walking.
“I would ask residents in these communities to check their gardens, streets and outhouses for any signs of Mr Green.
“I would urge anyone who may have seen Robin, or who has any information on his whereabouts to contact officers through 101 quoting reference number 3473 6th May.”