Seeds of Phoenix sylvestris Roxb (Palmae), and Tricosanthes dioica L (Cucurbitaceae) were investigated for their in vitro antibacterial activity against few gramnegative and gram-positive bacteria. Extracts of the plant seeds were prepared in methanol, ethanol, and chloroform by microwave assisted extraction method. Their antibacterial activity was investigated by disc diffusion and broth dilution methods. Ethanol extract of P. sylvestris was found active (bacteriostatic) against both grampositive and gram-negative organisms with MIC (minimum inhibitory concentration) values of 481 and 410 ?g/mL against Salmonella paratyphi A and Staphylococcus epidermidis, respectively. Phytochemical screening revealed presence of phenols, alkaloids, and flavones in it. This study indicated various extracts of P. sylvestris, and T.dioica seeds to possess antibacterial activity.