Sixty-six sera from leprosy patients, 42 with lepromatous leprosy (l.l.) and 24 with tuberculoid leprosy (t.l.) were examinated for the presence of e-antigen and e-antibody by immunodiffusion. The test for e-antigen was negative in all leprosy patients; e-antibodies were found in only three patients (4.5%) with l.l., all carriers of hepatitis B antigen. The HBsAg test was positive in 23.8% of the l.l. cases and in 12.5% of the t.l. cases; the anti-HBs was present in 38.1% of the l.l. cases and in 41.6% of the t.l. cases. The results suggest the possibility that the leprosy patients positive for the surface B antigen represent a very low risk and can be considered as chronic asymptomatic carriers of HBsAg.