A double-blind, randomized, controlled trial has been undertaken to evaluate treatment of chronic hepatitis type B with levamisole. Ten patients received levamisole (150 mg/day, 3 days/wk) and 10 received placebo until seroconversion to antibody to hepatitis B e antigen eventually occurred, or for a maximum of 18 mo. Final evaluation at 24 mo after starting treatment revealed that 60% of the patients in the levamisole group had become hepatitis B e antigen negative, 90% were hepatitis B virus–deoxyribonucleic acid negative in serum, and 8 of 9 (89%) patients had cleared hepatitis B core antigen from the liver. On the other hand, in the placebo group only 4 of the 10 subjects (40%) were hepatitis B e antigen and hepatitis B virus–deoxyribonucleic acid negative in serum and 3 of 8 (37.5%) of them became hepatitis B core antigen free in the liver. Moreover, in 8 patients of the treated group and in 4 of the control cases amino-transferase activities fell into the normal range. A liver biopsy specimen was obtained after treatment in 17 patients and 7 of 9 levamisole recipients showed marked improvement in hepatic histology, compared with 3 of 8 placebo recipients. These data show that patients treated with long-term levamisole therapy have a tendency toward normalization of aminotransferase activities and suppression of hepatitis B virus replication, suggesting that the drug may be of benefit in chronic hepatitis B e antigen-positive hepatitis.