Abstract: Compatibility and synergism of Bacillus thuringiensis commercial formulation and lambda-cyhalothrin were evaluated for the control of Helicoverpa armigera (Huebn.). Concentration-mortality response of 3rd instar H. armigera larvae due to B. thuringiensis Berliner subsp. kurstaki (Costar WP) and lambda-cyhalothrin (Karate 2.5 EC) alone and in combination with various concentrations incorporated in artificial diet was assessed. Combinations of low dosage of lambda-cyhalothrin and Costar (B.t.k.) formulations were found highly compatible and synergistic. In combination treatments (Costar+karate LC0, Costar+karate LC10 and Costar+karate LC25), the LC50s of Costar underwent 1.3, 3.4 and 3.4 fold reductions respectively. Further laboratory test and field trials of B. thuringiensis var. kurstaki supplemented with other chemical insecticides against chickpea pod borer are warranted.