Upon admission to the hospital, 7,984 patients were tested for hepatitis B surface antigen (HBsAg) by radioimmunoassay. Seventy-one patients had sera positive for HBsAg. Twenty-four (34%) were possible asymptomatic carriers in whom liver function was not further evaluated and occult liver disease could not be excluded; 16 (23%) had either a previous history or admitting diagnosis of hepatic dysfunction; eight (11%) had occult liver disease, revealed after HBsAg antigenemia was discovered; and 25 (34%) were unsuspected asymptomatic carriers whose liver function was normal. We concluded that screening for HBsAg was an effective preventive tool in identifying HBsAg-positive patients. Screening solely for the detection of occult liver disease is not an effective method because of the high cost. Perhaps because of the unsolicited nature of this data collection, screening for HBsAg was not clinically effective for the majority of patients, as evidenced by the high incidence of inadequate clinical evaluations and lack of serologic follow-up. Proposals to alleviate ineffectiveness are discussed.