Cimolomys (Greek for "chalk mouse") is a mammal genus from the Upper Cretaceous of North America.

Fossil remains were found in Campanian-Maastrichtian (Upper Cretaceous) strata of Texas and Wyoming (United States).

Remains were found in Maastrichtian (Upper Cretaceous) strata of Montana, South Dakota and Wyoming (USA) and Saskatchewan, Canada.

in 1993.. Remains were found in Campanian (Upper Cretaceous) strata of Mill Creek, Utah (USA).

Remains were found in Maastrichtian (Upper Cretaceous) strata of North America.