The sheriff's office said 60-year-old Patrick Serzynski was hunting on Fourth Lake in unincorporated Lake Villa Monday morning and hasn't been heard from since.
His boat and personal property was found at his duck blind, but there was no sign of the man.
The sheriff's office was searching the marshy area around the lake and the lake itself. The search was called off due to darkness around 7 p.m. and will resume shortly after daybreak Tuesday.