Evidence of bacillaemia through examination of heparinised blood smears was obtained in 17 of the 20 cases (85%) of untreated leprosy cases belonging to the spectrum ranging from BT to LL. Among 17 cases whose blood smears were positive for AFB, the endothelial cells of blood vessels in skin lesions showed AFB in 11 instances (64.7%) and in 7 (41.2%) of these cases biopsies obtained from apparently normal skin also showed bacilli in the blood vessels. The fact that blood smears may show AFB even in patients belonging to types classifiable as BT-BB in the Ridley Jopling scale (a child aged 3 1/2 years showed this feature) emphasises the importance of investigations to assess thoroughly the extent of bacillation in leprosy patients.