Most practical and cheap techniques other than mass surveys to detect leprosy in urban slums are still not known. The population inhabiting a large somewhat isolated slum in North Bombay was exposed to intensive health education programmes over a period of two years. Leprosy cases reporting as a result of these measures as well as those detected by trained workers casually or through contact examination were registered at two weekly clinics conducted within the slum. A total of 184 patients out of whom 27 were smear +ve, were identifiable by these means. The population of the slum was found to be 18228. Total prevalence rate of leprosy after examining 14723 subjects in the colony was revealed to be 24 per 1000 (smear +ve cases: 2.2. per 1000) out of which a prevalence of 12.4 per 1000 (smear +ve cases: 1.8 per 1000) had actually come to our knowledge even before instituting mass surveys. The results of this study indicate that in comparable urban situation it should be possible to identify 54% of total leprosy cases by techniques other than surveys. More significantly a striking feature of this study is that 82% of cases of true public health significance namely smear +ve patients could be unearthed by these means.