The aim of the study was to assess the prevalence of depression among Croatian patients infected with human immunodeficiency virus (HIV) and to make a comparison with patients with other acute and chronic infectious diseases. We assessed the depressive disorder using the Beck Depression Inventory questionnaire (BDI), without clinical confirmation. The BDI scores were examined in 80 HIV-infected persons and compared to 80 persons with chronic viral hepatitis and 78 with acute infectious diarrhea. All examinees were treated as outpatients at the University Hospital for Infectious Diseases in Zagreb in March and April of 2003. Prevalence of moderate and severe depression among HIV-infected was 16/80 (20%) with a 95% confidence interval 11% to 29%. Male patients with HIV or chronic viral hepatitis had a significantly higher BDI scores than males with acute infectious diarrhea (p = 0.017, Kruskall-Wallis, d.f. 2). Female patients with HIV infection tended to have a lower BDI score than females with chronic viral hepatitis or acute infectious diarrhea (p = 0.087, Kruskall-Wallis, d.f. 2). Prevalence of moderate and severe depression among Croatian HIV-positive patients is higher than the upper estimate for general population. Croatian males with chronic infectious disease have higher rate of depression than those with acute infectious disease.