Cluster of fulminant hepatitis B in crack users. Fulminant hepatitis occurs in only 1% of acute hepatitis B patients, requiring hospitalization, but coinfection with delta virus increases the incidence. Hepatitis B and D infection are commonly associated with intravenous drug abuse, but there have been no previous reports of an association with nonparenteral cocaine. Crack use, via sexual promiscuity, is associated with an increased risk for human immunodeficiency virus infection, but has never been associated with viral hepatitis. We report four fatal cases of fulminant hepatitis B including, one with delta virus coinfection and one with human immunodeficiency virus (HIV) infection, in young, sexually active, heterosexual crack users. These patients denied a history of intravenous drug abuse. Our patients probably contracted hepatitis B infection via heterosexual contact. Chronic cocaine exposure may or may not have contributed to the fulminant outcome. Crack users may be at increased risk of developing hepatitis B and D infection. Epidemiological studies are needed to evaluate their risk of viral hepatitis and the effect of cocaine on its outcome. 