One hundred eighty-eight asymptomatic addicts were studied to determine the frequency of a history of hepatitis (previous episodes of jaundice), abnormalities of liver tests (serum bilirubin, alkaline phosphatase, serum albumin, serum glutamic oxalacetic transaminase) and incidence of HB-Ag and HB-Ab. Seventy-four were white and 114 were nonwhite. A history of hepatitis was obtained in only 38%. One hundred and fifty-two of the 188 addicts (81%) had one or more abnormal liver tests. The bilirubin was abnormal in 5%, akkaline phosphatase in 28% and serum glutamic oxalacetic transaminase in 55%. HB-Ag was positive in 2.6% using radioimmunoassay and HB-Ab was found in 66%. There was a higher incidence of elevated serum glutamic oxalacetic transaminase, HB-Ab and history of hepatitis among white, compared to nonwhite addicts.