The authors reviewed retrospectively 139 splenopathies detected during 432 US examinations of the abdomen in AIDS patients to assess the role of US in correlation with anamnestic-clinical data and histologic findings in 45 cases. Splenomegaly was the main sign of abnormal splenic conditions, since it was present in all the examined patients. Twenty-one cases exhibited focal lesions. Non-Hodgkin's lymphomas were the only kind of neoplastic condition, which were detected in 15% of cases. In 57% of cases splenopathy was correlated with an infective agent, with a marked prevalence of Mycobacteria-i.e., tubercular in 26% and atypical in 22%. In the splenopathies with histologic confirmation which exhibited a focal US pattern (47%), US proved to be useful in assessing splenic involvement, however aspecific its signs, and in its monitoring, especially in the lesions with unexpected colliquative evolution, as in two cases of atypical mycobacteriosis.