Abstract: Bio-efficacy of Beauvaria bassiana, an entomopathogenic fungus, was evaluated against tea looper caterpillar, Buzura (=Biston) suppressaria Guen. (Geometridae:  Lepidoptera) at Kamalpur and Hunterpara Tea gardens, West Bengal, India, during May-June, 2005 & 2006. Methomyl 40% SP and cypermethrin 25% EC, the planters' commonly used chemical pesticides were taken as standard checks. B. bassiana  was used at 1.50 g, 2.00 g and 2.5 g/lit. of water while methomyl and cypermethrin were used at 0.75 mL, 1.00 mL and 1.50 mL and 0.50 mL, 1.00 mL and 1.50 mL/lit. of water, respectively. There was 88.00% reduction in the population build up of looper caterpillar at Kamalpur Tea Garden and 84.00%  at Hunterpara Tea Garden at 3 days after spraying with 2.5 g B. bassiana/lit. of water. The dead caterpillars turned black and hanged under the leaves. However, the biocidal activity of B. bassiana was found to be on par with the highest dose of methomyl and cypermethrin.