Liver abscess requires prompt therapy but frequently accompanies or mimics other causes of inflammation in the right upper quadrant, and identification may be obscured by associated medical conditions. Ninety-two patients with liver abscesses due to pyogenic (n = 20) or amebic (n = 72) infections were treated at the Harbor-UCLA Medical Center. Admitting diagnoses were acute biliary tract disease in 25 patients, hepatic abscess in 21, hepatitis in 16, appendicitis in 9, and other diseases in 21. Forty patients had major associated medical illnesses. Correct diagnosis of liver abscess was made by a noninvasive radiologic test in 82 patients, laparotomy in 8 and autopsy in 2. Ultrasound-guided percutaneous aspiration was used as an adjunct to management in 17 patients. Diagnosis of liver abscess was confirmed within 24 h of admission in more than half of the patients. Clinical suspicion and an orderly application of radiologic tests provide the key to early diagnosis and therapy. Ultrasonography has an accuracy above 90% and is the screening test of choice, particularly when calculous biliary tract disease figures in the differential diagnosis. The hepatic phase of the HIDA scan may reveal an unsuspected abscess when acute cholecystitis is considered. Computed tomography and liver-spleen scan are useful in selected patients with chronic disease. This strategy will insure speedy diagnosis and minimize cost and length of hospitalization.