408 skin smear negative paucibacillary leprosy cases who had completed six months MDT were kept under surveillance for three years. The clinical assessment at the end of surveillance showed that 276 (82%) of all the cases attained inactivity. Two patients who were inactive showed signs of relapse. Five patients showed more activity though they were regressing under treatment. The inactivity rate was much higher amongst the patients with 1 to 3 skin lesions (88%) as compared to the patients with greater than or equal to 4 lesions (60%). The difference was statistically significant (P less than 0.001). The past treatment before MDT did not appear to influence the clinical course of the disease. 17% of the patients essentially border-line type continued to show signs of activity even after 3 years surveillance indicating the need for triple drug therapy (to be treated as multibacillary). However large scale data on relapse rate would be essential before the efficacy of WHO short-term therapy for paucibacillary leprosy is evaluated.