Huntington's disease (HD) is a devastating central nervous system disorder. Even though the gene responsible has been positionally cloned recently, its etiology has remained largely unclear. To investigate potential disease mechanisms, we conducted a search for binding partners of the HD-protein huntingtin. With the yeast two-hybrid system, one such interacting factor, the huntingtin interacting protein-1 (HIP-1), was identified (Wanker et al. 1997; Kalchman et al. 1997) and the human gene mapped to 7q11.2. In this paper we demonstrate the localization of the HIP1 mouse homologue (Hip1) into a previously identified region of human-mouse synteny on distal mouse Chromosome (Chr) 5, both employing an IRS-PCR-based mapping strategy and traditional fluorescent in situ hybridization (FISH) mapping.