Pseudomonas aeruginosa is an opportunistic pathogen, accounted for causing large number of serious infections. Due to emergence of multidrug resistant species the treatment of pseudomonal infections has become complicated. The cross-sectional observational study was performed from March 2012 to July 2012. 100 clinical isolates of Pseudomonas aeruginosa were obtained from in-patient and out-patient’s samples collected from various sites by clinical laboratory of reputed tertiary care hospital of Karachi. The Kirby Bauer Disc Diffusion Method was used to determine the antibiotic susceptibility. The highest percentage of Organism was isolated from Urine sample (23%). Prevalence of pseudomonal infection gender-wise showed Female (58%) and Male (47%) were found to be infected. The age group of 71-100 yrs. in Male and 51-70 yrs. in Female were found to be more prone to pseudomonal infections. Pseudomonas aeruginosa sp. showed highest resistance against Colistin (42%) followed by Sulzone (39%), while it exhibited intermediate resistance to Aztreonem (32%). Tazo-pipercillin and Amikacin conferred sensitivity of 83%, 74% respectively. The sp. isolated from urine sample was highly sensitive to Amikacin (73.9%); More than 85% of sp. isolated from Tracheal aspirate was sensitive to Colistin and Sulzone. Imipenem and Tazo-pip, both were highly effective against more than 80% of sp. isolated from Pus specimen.