SummaryThe observation in Brussels of a ease of kala azar imported from Spain led us to the following considerations: l°kala azar remains sometimes undiagnosed or clinically confused with malignant lymphoma or leukaemia;2°diagnosis of kala azar must be evoked whenever medical history reveals a stay in endemic regions; in this respect, clinicians must be aware that kala azar is endemic in all the mediterranean urea, including southern France; 3°for the last 15 years, in most of the mediterranean countries, kala azar seems to occur at least as frequently in adults as in children; 4°the clinical expression of the disease may be mild at the beginning: splenomegaly may be discrete, hypergammaglobulinaemia may be lacking; 5°definite diagnosis is based on the discovery of the parasite; bone marrow aspiration represents the safest and simplest diagnostic procedure; 6°the discrepancy in frequency of subclinical and full-blown forms of infection byLeishmania donovaniraises a fundamental question, not completely resolved at the present time: does a latent immunodeficient state favour the development of severe forms of kala azar ?