Macrophage cultures from the peripheral blood were performed in 25 untreated bacteraemic leprosy patients. The monocytes on conversion to macrophages in culture continued to harbour solidly stained M. Leprae till the termination of culture. It is suggested that the majority of these bacilli are viable and capable of multiplication intracellularly in macrophages if cultures could be maintained for sufficiently long periods. It was observed that bacteraemia in Leprosy can be detected by the culture technic. It has been found to be more sensitive than the leukocyte adherence method.