Manuel Oliveira is 80 years old and was last seen Thursday afternoon around 4 p.m.
Police are concerned because of the length of time he's been missing, but also because he is diabetic and suffers from the early stages of dementia.
Sgt. David Coffey says police believe he may still be in the Kensington area.
"The length of time is concerning, he's been out all night," said Coffey. "We're hoping he's close to where he was last seen, but we haven't determined that yet."
Oliveira is white, five-foot-eight inches tall, weighs about 190 pounds, with brown eyes and grey hair on the sides.
He is wearing a grey fedora and a dark three-quarter length coat, dark pants, and black shoes. He uses a walker.
Anyone who sees him should call police.