The retinoblastoma interacting zinc finger gene RIZ is a member of the recently discovered PR domain family that includes the MDS1-EVI1 breakpoint gene involved in human leukemia. To help understand the role of RIZ in human diseases, we have determined the cytogenetic and physical localizations of the RIZ gene. Using fluorescence in situ hybridization, we determined that RIZ maps to 1p36. On the physical map, RIZ is adjacent to the polymorphic marker D1S228. We suggest that the RIZ gene may be a candidate target of 1p36 alterations that commonly occur in neuroendocrine, breast, liver, colon, and lymphoid tumors.