Genetically anemic W/Wv mice and lethally irradiated wild-type mice were cured and populated by grafted marrow cells from donor mice of three congenic lines that differed at non-H-2 histocompatibility loci. Tail skin from mice of the same congenic lines was grafted 3-4 weeks later. In two cases, the recipients behaved as expected, no longer rejecting skin syngeneic with the marrow graft that had repopulated them. However, B6-H-24c skin was rejected by WBB6F1-W/Wv mice that were cured with B6-H-24c marrow showing a mean survival time of 9.9 weeks. It was rejected somewhat faster, with a mean survival time of 5.9 weeks, by W/Wv mice cured with marrow from other types of donors. Results were more variable in lethally irradiated WBB6F1-+/+ recipients of B6-H-24c marrow, but they also rejected B6-H-24c skin. Both types of recipients remained chimeras after the skin was rejected, showing more than 90% of the B6-H-24c hemoglobin type. This is the first report of a Skn gene in a congenic line