We have found human DNA to contain a number of sequences related to simian sarcoma associated virus (SSAV). One of these sequences was isolated from a human genomic library. The molecular clone, termed S71, contains regions homologous to SSAV gag and pol fragments and SSAV LTR. Furthermore, hybridization experiments and DNA sequencing revealed distinct homologies to the reverse transcriptase coding region of several other retroviruses including baboon endogenous virus (BaEV) and murine leukemia viruses (MuLV) as well as retrovirus-like elements. Some sequence homology was also found with the C-type retrovirus-related multicopy human clone 4-1. S71 is present in only one copy per human genome equivalent and exhibits an EcoRI restriction fragment length polymorphism.