Fluorescence in situ hybridization (FISH) was applied, using genomic DNA clones, to precisely localize the genes for GPI, CRC, LIPE, and GH on pig chromosomes. The porcine CRC gene was localized to band 6q12 using both genomic and cDNA clones. The GPI and LIPE genes, which are closely linked to the CRC gene, were also mapped to the same band (6q12), using genomic lambda clones. The mapping data are a refinement of earlier findings, wherein radioactive in situ hybridization was used and the assignments included both the short and long arms. Results of the present study clearly exclude the short arm as the location for the three genes. Further, using a genomic cosmid clone, the GH gene was mapped to band 12p14. Compared to the earlier assignments, which included almost the entire short arm of the chromosome due to the use of radioactive in situ hybridization, the present FISH findings provide a band-specific localization for the gene. A modified, simpler version of the posthybridization trypsin/EDTA banding method is also presented.