Fifty-nine-year-old Steven Langlands was last seen leaving his home on Second Avenue, Unanderra, about 9am on Monday.
Lake Illawarra Police were notified of his disappearance and commenced inquiries into his whereabouts.
There are concerns for his welfare as he has medical conditions.
Steven is described as being of Caucasian appearance, about 175cm tall, of medium build, with short grey hair.
He was last seen wearing a black Mitsubishi polo-shirt, Khaki-coloured shorts and red runners with white soles.
Police are urging anyone with information about his whereabouts to contact Crime Stoppers on 1800 333 000.