[show abstract][hide abstract] ABSTRACT: The present study was carried out to evaluate and compare the antibacterial susceptibility of Gram-positive and Gram-negative bacteria to Cyrocin (Ciprofloxacin). The following three bacterial strains were used: Staphyloccocus aureus [ATCC 25923], Escherichia coli [ATCC 25922] and Pseudomonas aeruginosae [ATCC 27853]. Standard commercial discs of definite potency are used as reference standard (Ciprofloxacin 5g [CTO425B - OXOID Ltd. UK]). The test products were 250 mg and 500 mg tablets of the following brands: Cyrocin (Highnoon Laboratories Limited), Ciproxin (Bayer Pharma (Pvt) Ltd. – Pakistan), Mercip (Merck Marker (Pvt.) Ltd., Pakistan) and Axcin (Sandoz - Norvatis Pharma Ltd., Pakistan). The media used were: Nutrient Broth (Cat. No. 1.05443, Merck, Germany) and Mueller Hinton Agar [Oxoid]. The study showed no statistically significant difference in the results of different brands.