The correlation between the serotypes and sensitivity distribution of Pseudomonas aeruginosa was studied with stock strains of department, strains isolated from various clinical sources and strains of haspital environment of the past two years. Two hundred and fifty seven strains were typable and 38 strains were untypable out of 295 clinical sorces. Serotype B was most provalent(27.6%) followed by serotype G(24.9%), serotype E(23.3%) and serotype A(7.8%) among 257 typable strains. However, no serotype J,L and M were observed. Serotype B,G,E and A were isolated from pus, sputum, wound, burn site and urine. Serotypes E were most frequently isolated from nasal discharge and serotypes K were isolated from pus. There were no apparent differences in sensitivity distribution of streptomycin, carbenicillin and ampicillin between the clinical and The environmental origin. However, the strains of environmental origin were found to be relatively more susceptable to tetracycline, gentamicin and fradiomycin than the strains of clinical sources in high concentration. The strains of clinical sources of serotype B,G,E and A showed different resistant patterns to all antimicrobial agents except for carbenicillin. Serotype E showed the highest percentage resistance followed by serotype G,B and A.