Recently two main genetic maps [Rohrer et al. Genetics 136, 231 (1994); Archibald et al. Mamm. Genome 6, 157 (1995)] and a cytogenetic map [Yerle et al. Mamm. Genome 6, 175 (1995)] for the porcine genome were reported. As only a very few micro-satellites are located on the cytogenetic map, it appears to be important to increase the relationships between the genetic and cytogenetic maps. This document describes the regional mapping of 100 genetic markers with a somatic cell hybrid panel. Among the markers, 91 correspond to new localizations. Our study enabled the localization of 14 new markers found on both maps, of 54 found on the USDA map, and of 23 found on the PiGMaP map. Now 21% and 43% of the markers on the USDA and PiGMaP linkage maps respectively are physically mapped. This new cytogenetic information was then integrated within the framework of each genetic map. The cytogenetic orientation of the USDA linkage maps for Chromosomes (Chrs) 3, 8, 9, and 16 and of PiGMaP for Chr 8 was determined. USDA and PiGMaP linkage maps are now oriented for all chromosomes, except for Chrs 17 and 18. Moreover, the linkage group "R" from the USDA linkage map was assigned to Chr 6.