A bioactivity monitored phytochemical examination of the morphological parts of Mallotus oppositifolium utilizing the hole-in-plate bioassay procedure against gram-positive, gram-negative bacteria and fungal isolates resulted in the location of significant antimicrobial activity in the acidic fraction (HAF) of the hexane extract of the powdered leaves. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were 32.5 microg/ml and 65 microg/ml against Pseudomonas aeruginosa NCTC 6750 and 25 microg/ml and 50 microg/ml against Staphylococcus aureus NCTC 6571 respectively. These activities were found comparable with standard drugs.