Hepatitis B surface antigen (HBsAG) and antibody (anti-HBs), and antibody to the hepatitis B core antigen ( anti-HBc) were measured by radioimmunoassay in 46 current or former narcotic users who underwent liver biopsy for evaluation of chronic liver disease. Significant alcohol abuse was found in 38 narcotic users (82.6%). On liver biopsy, 24 had cirrhosis (52.2%), nine had chronic active hepatitis (19.6%), five had lipid accumulation (10.9%) and eight had other diagnoses (17.4%). At least one marker for hepatitis B was found in 45 of 46 narcotic users (97.8%). Five had HBsAg and anti HBc (10.9%), one had anti-HBs alone (2.2%), 30 had anti-HBs and anti-HBc (65.2%) and nine had anti-HBc alone. Although almost all narcotic users with chronic liver disease have active or resolved hepatitis B infection, alcohol abuse appears to be the major factor in the development of cirrhosis in the subset of narcotic users studied.