Joseph McAlees left his Kilwinning home around 4.30pm to visit relatives in Greenock, however, his family has had no contact since then.
The 63-year-old routinely takes medicine and it is unknown if he has his medication with him.
Mr McAlees is described as a white man with a local accent, approximately 5ft 8in tall and has a medium build with short hair. You can see him on the photo.
When he was last seen he was wearing glasses, a pale blue Adidas jacket, blue jeans and black Nike trainers. He was also wearing a blue Adidas back pack and a black holdall.
Officers from Irvine police office can be contacted via the non-emergency 101 number.
Police are appealing for anyone with information to come forward as concern for his well-being is growing among his worried family.
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