Isoenzymatic characterization was done on 100 isolates obtained from visceral leishmaniasis (VL) patients coinfected with human immunodeficiency virus (HIV); isolates had been received between 1986 and 1993 at the International Leishmania Cryobank and Identification Centre in Montpellier, France. Electrophoresis was done with 15 isoenzymes using the starch gel technique combined, where appropriate, with isoelectrofocusing. Nine Leishmania infantum zymodemes were identified; L. infantum zymodeme MON-1, the most common parasite of human VL in the Mediterranean basin, was the most frequent in coinfections. It could also occasionally be responsible for localized cutaneous leishmaniasis lesions. Several dermotropic zymodemes, which were responsible for localized cutaneous leishmaniasis in immunocompetent patients, caused VL in HIV-positive patients. In addition, in 10 patients, a second isolate obtained during relapses occurring between 1.5 and 9.0 months after treatment was identical to the original isolate.