Leishmania were isolated from Peruvian patients with uta or espundia; genomic DNA was examined for restriction fragment length differences by Southern blot analysis using DNA probes for β-tubulin and for the major surface antigen gp63. Using 5 different restriction endonucleases, Peruvian isolates show homogeneity when examined at the β-tubulin locus. In contrast, the organisms demonstrated heterogeneity both within and between disease groups when examined for restriction site differences within the gp63 locus. The differences observed did not correlate with the 2 disease groups. Comparison of these Peruvian isolates to New World reference strains of the Leishmania braziliensis complex reveals no consistent pattern of identity with either L. b. guyanensis, L. b. panamensis, or L. b. braziliensis.