Deletion of DNA sequences from various regions of the short arm of human chromosome 3 (3p13-14, 3p21, and 3p25) has been observed during the development of a variety of solid tumors, including lung and renal cell carcinomas. In this study we have used a set of radiation fusion hybrids to generate a physical map of chromosome 3p to orient the search for putative tumor suppressor genes. Eighty-six human-hamster radiation fusion hybrids were screened on Southern blots for the retention of 55 human chromosome 3p DNA markers. The high marker density enabled us to identify a set of successively overlapping chromosome fragments in the 3p13-22 area guided by eight markers with previously known order. Twenty-four map intervals were suggested using breakpoints determined by partial fragment overlaps. The final order between the markers derived is consistent with previous information about localizations for 26 of the markers to three larger cytogenetic intervals.