The murine tumor rejection antigen gp96 (TRA1, mapped to mouse chromosome 10) is a member of the heat shock protein family. Using a fragment of the murine gp96 cDNA as a probe, three gp96-related human genes have been isolated and structurally characterized. They have been mapped to human chromosomes 1 (p22), 12 (q24.2-->q24.3), and 15 (q25-->q26) by Southern blot hybridization and in situ hybridization of gene-specific probes. Only one of the genes, designated TRA1 (human chromosome 12) is a coding gene; the other genes (TRA1P1 and TRAP2) appear to be independently derived, processed pseudogenes.