Antibacterial activity of Nyctanthus arbor tris-tis (Linn), an important medicinal plant belonging to the family Oleaceae. The antibacterial activity was studies in leaf against three gram negative bacteria (E.coli, Klebsiella pneumonia and Pseudomonas aeruginosa) and three gram positive bacteria (Staphylococcus aureus, Bacillus subtilis and Corynebacterium glutaminum). The maximum activity of the plant extract against gram negative bacteria shows the possibility of developing drug against the diseases produced by gram negative bacteria. Inhibition effect of E.Coli, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia, Corynebacterium glutaminum, pseudomonas aeruginosa has various solvent extract of Nyctanthus arbor tris-tis. This suggests that extract from the plant have broad spectrum of activity against tested bacteria. Moreover, these leaves extracts also tested for their antibacterial activity against inhibitory effect on growth of these isolated bacteria. Hence this study also enhances the nutrition value of leaves because Nyctanthus arbor tris-tis provide the resistance against some kind of bacteria.