Abstract: Antimicrobial activity of Nigella sativa against Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae (ATCC 19615), Escherichia coli (ATCC 25922) and Bacillus cereus (ATCC 11778) were investigated. The seed extracts were prepared by the methanolic wetting extraction method. Filter paper discs impregnated with varying concentrations of N. sativa extract were tested by the disk diffusion method. The inhibition zones of the Mueller Hinton agar in different extract concentration showed that at 25 mg/20 μL, 50 mg/20 μL and 100 mg/20 μL, the inhibition zones increased accordingly in S. aureus and P. aeruginosa. However, N. sativa was found to be inactive against ESBL producers (E. coli, K. pneumoniae and B. cereus).