The effectiveness of a BCG vaccination programme in protecting against leprosy was assessed by case-control and cohort analyses of data from the Lepra Evaluation Project in Karonga District, Northern Malawi. Results indicate that BCG provides at least 50% protection against leprosy in this population and that protection is independent of age, sex, schooling status, or location within the project area. Agreement between these findings and those from a controlled trial in Uganda indicates that BCG is sufficiently effective against leprosy in East and Central Africa to be considered an important element of leprosy control in that region.