Visceral leishmaniasis (VL) focus in the Ordubad District of the Nakhichevan ASSR has become active for the last years. Complex study of the focus, performed in 1985-1987, allowed to establish the following: VL causative agent, circulating in the Ordubad District belongs to the Leishmania infantum species. It was identified by isoenzymatic analysis (for 12 enzymes) and the Adler serological test. Disease cases prevailed in the upper part of the town of Ordubad and were confined to a small area (4 adjoining streets). Little children (up to 2 years old) prevail among patients. Spatial distribution of the disease correlated with indirect EIA data on healthy urban population (3116 persons examined) and stray dogs (152 animals examined). Mean percentage of positive assay results for the titers ranging from 1:80 to 1:20 was 8.0, for human population of Ordubad, and 19.1 for the dogs. Ten Phlebotominae species were found in Ordubad and its suburbs: Phlebotomus (Laroussius) major, Ph. (L.) kandelakii, Ph. (Adlerius) halepensis, Ph. (A.) balcanicus, Ph. (Phlebotomus) papatasi, Ph. (Paraphlebotomus) sergentii, Ph. (Par.) caucasicus, Ph. (Par.) alexandri, Sergentomyia dentata, S. palestinensis. Authors suggest that stray dogs are reservoirs of infectious agents in the Ordubad focus, while Phlebotominae of the Laroussius and Adlerius subspecies are disease carriers, the disease being regarded as a Mediterranean form of visceral leishmaniasis.