Clofazimine is an important and effective constituent of multi drug therapy for leprosy. A study has been conducted to determine the distribution of clofazimine in maternal milk so that the safety of breast-feeding during maternal ingestion of the drug can be ascertained. Eight female leprosy patients (LL/BL) on clofazimine, 50 mg daily or 100 mg on alternate days for 1-18 months, (mean 5.0 +/- 1.81 months; median 3.25 months) and in the early lactating phase were studied. Blood samples and milk specimens were collected 4-6 hr after the last daily dose. Clofazimine was assayed in the milk and plasma samples by HPTLC. Mean plasma and milk clofazimine levels were 0.9 +/- 0.03 micrograms/ml and 1.33 +/- 0.09 micrograms/ml respectively. The ratio of milk to plasma drug concentration ranged from 1.0 to 1.7 with a mean of 1.48 +/- 0.08. The amount of drug ingested by the infants was 0.199 +/- 0.013 mg/kg/day which represented 22.1 +/- 1.9% of the maternal dose.