The Rowett nude gene (RONU) has been mapped on rat chromosome (Chr) 10 by linkage analysis using (ACI x F344/N-RONU/RONU)F1 x F344/N-RONU/RONU backcross progeny. The gene order on the chromosome was RR92- (16.1 cM) - RR24 - (17.9 cM) - MYHSE (myosin heavy chain, embryonic) - (1.0 cM) - SYB2 (synaptobrevin 2) - (1.0 cM) - SHBG (sex hormone-binding globulin) - (4.0 cM) - RONU (Rowett nude) - (29.0 cM) - AEP (anion exchange protein), PPY (pancreatic polypeptide) - (3.0 cM) - ACE (angiotensin I converting enzyme), GH (growth hormone). The RONU locus was localized to 10q24-->q32 by fluorescence in situ hybridization of the closely linked SYB2 and loosely linked GH loci on the opposite side. Conserved linkage of homologous loci mapped to rat Chr 10 and mouse Chr 11 supports the hypothesis that the RONU locus is a rat homolog of the mouse nu locus.