The present study was designed to screen antimicrobial activity of Manilkara zapota (L.). Bioassays for antimicrobial activities were carried out using ethyl acetate extracts of both stem bark and leaves of Manilkara zapota against some pathogenic bacteria and fungi. TLC (Thin layer chromatography) profile of isolated extracts showed the presence of terpenoids, glycosides and flavoniods type compounds. The ethyl acetate extract of stem bark exhibited antimicrobial activity against all the pathogenic bacteria used in this study and also showed activity against Aspergillus flavus, Vasianfactum sp and Fusarium sp. with inhibition zones in the range of 08-16 mm. Ethyl acetate extract of leaves possessed mild activity against Bacillus subtilis, Bacillus megaterium, Sarcina lutea, Escherichia coli and Salmonella typhi. The minimum inhibitory concentrations (MICs) of the extracts were found to be in the range of 256 ~ 512 ìg/ml. The cytotoxicity (LC50) against brine shrimp nauplii (Artemia salina) were also evaluated and found to be 16.17 ìg/ml for ethyl acetate extract of leaves, 50.26 ìg/ml for ethyl acetate extract of stem bark and 12.38 ìg/ml for ampicillin trihydrate.