A survey of rodents and dogs was carried out in Alexandria and its environs to see if an animal reservoir was associated with an outbreak of infantile kala-azar in this area. Three rodent species, Rattus rattus, Rattus norvegicus and Mus musculus, were commonly trapped and examined. A flagellate parasite was isolated from the spleens of two R. norvegicus. It was typed serologically by excreted factor serotyping and enzymologically by thick starch electrophoresis of four of its enzymes: GPI, G6PD, 6PGD and PGM. The same type of parasite was also isolated from two stray dogs from the same vicinity. This flagellate was quite distinct from Leishmania donovani, Leishmania major and Leishmania tropica, the three common Old World species of Leishmania; but its exact identity remains uncertain. It could be a new leishmanial entity or a flagellate parasite of another genus.