The antibocterial results of this study showed that the oscillatoria sp. Extract(100mg/ml) showed highest zone of inhibition 22mm against P. aeruginosa followed dy E. coli20mm, B. subtilis19mm and S. aureus15mm which the gram positive bacteria are more susceptible than gram negative bacteria to methanolic extract of Oscillatoria sp. The MIC values of Oscillatoria sp. Methanolic extract showed 30 µg/ml concentration against B. subtilis and P. aeruginosa This minimal concentration is preferably controlled the bacterial growth. According to that our study explores Oscillatoria sp. Ethanolic extract effectivey inhibits the growth of human pathogenic bacteria such as B. subtilis and P. aeruginosa.