In the present study, sera of 56 children suffering from visceral Mediterranean leishmaniasis were analysed. The incidence of circulating immune complexes (CIC) by ELISA technique using the conglutinin binding assay was 39% before treatment, 28% after the first treatment, and nil at the end of the second one. The C4 levels remain low even after treatment. The anti-leishmania antibodies (AAL) account for 95% of the cases before treatment and 84% after treatment. The rheumatoid factor (FR) also remains with more or less the same frequency (74%) before and after treatment. The search for a correlation between the presence of CIC and the other immunological factors show that the average titre of AAL is higher in the group of patients that have CIC than in the group that does not. The C4 levels are significantly reduced in the CIC positive group of patients, whereas the rate of IgG is significantly increased in the same group. The study of the evolution of CIC under treatment in nine patients shows that they disappear at the end of the treatment, and that the FR reduces but does not disappear.