Police hope to get help from the public to find Ross McKendrick, who was last seen on New Year's Eve.
Detective Sergeant John Wilson of the Rotorua CIB said the 65-year-old had gone missing from his Western Heights home.
"He was last seen leaving his home on a blue bicycle. He has not been seen or heard from since."
Mr McKendrick suffered from a number of serious health issues. which required constant medication, he said.
"Police believe he was in the Blue Lake area at 6.45pm on December 31."