Twenty-nine Leishmania infantum strains characterized by different host source, tropism and belonging to 6 zymodemes, were examined by restriction enzyme analysis of kinetoplast DNA (kDNA) using 15 endonucleases. The enzymes which produced only one fragment revealed full identity between all the strains examined, while those producing many bands gave different electrophoretic patterns. They were interpreted with the aid of numerical analyses (cluster and multifactorial analysis). The results show a cline of genetic variability among the strains, the highest similarity being observed between most of the viscerotropic strains isolated from man, dog, black rat and sandflies. The strain agents of human cutaneous leishmaniasis show a varying degree of genetic divergence from this group, which appears more evident when characters from isoenzymes are considered.