Raymond Dimonte, 62, and Martin Mendoza, 49, were swimming near the 63rd Street Harbor Sunday when they went missing.
Dimonte is described by police as 5'8" tall, 180 pounds with blue eyes and was last seen wearing black swimming trunks.
Mendoza is described by police as 5'6", 180 pounds and bald and was wearing gray cargo shorts when he went missing.
A Marine Unit searched for them Monday morning using sonar scanners to help in the search.
Anyone with information is asked to contact the Chicago Police Area One Special Victims Unit at (312) 747-8380.