Pyogenic hepatic abscess is often a serious disease, whose rates of cure are proportional to the timeliness of treatment and the correct use of antibiotics. The final choice of antibiotics should be guided by the results of a culture. Local cultures of pus are more often positive than blood cultures. It is essential to plan an effective treatment regimen when dealing with immunocompromised patients. Our results, regarding 85 patients with pyogenic liver abscess, 19 of which were immunocompromised, seen at our Department from 1980 to 1992, indicate that planning the therapy on the base of blood culture alone means a 78% risk of inappropriate treatment.