Medicinal plants have considerable widespread use as crude drugs in the primary health care of communities. Various plants have already been tested for their antimicrobial activity to discover new antimicrobial agents. In this investigation antimicrobial activities of aqueous and methanolic extracts of Heterophragma adenophyllum leaves and seeds were screened as these have been used since centuries in traditional medicine for the treatment of skin and urinary tract infections and also as antidiarrheol and antidiabetic agents. Preliminary phytochemical screening of Heterophragma adenophyllum leaves showed presence of saponins, alkaloids and glycosides while H. adenophyllum seeds contained flavonoids, alkaloids, glycosides, tannins and saponins. Testing of antimicrobial activity of aqueous and methanolic extracts of the plant was conducted at the concentrations of 1 and 2mg /disc against three gram-positive strains including Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633) and Staphylococcus epidermidis(ATCC 12228) and two gram-negative strains viz. Escherichia coli (ATCC 8739) and Pseudomonas aeroginosa (ATCC 27853) by disc diffusion method. The H. adenophyllum leaves showed maximum activity against S. aureus as the zone of inhibition was 22.37±0.32 mm but aqueous extract of the leaves showed no activity against S. epidermidis. The methanolic extract of H. adenophyllum seeds showed maximum activity against E. coli producing 16.33±0.31 mm zone of inhibition, but showed no activity against S. epidermidis. The aqueous extract of H. adenophyllum seeds showed maximum activity against S. aureus and S. epidermidis with 22.13±0.09 mm and 23.43±0.35 mm zones of inhibition. Furthermore, data obtained showed that there was a significant variation in the zones of inhibition produced by the test samples of the plant parts exposed to sunlight nakedly or wrapped in aluminum foils and those kept in cupboard when compared with controls kept unirradiated.