To analyze the major outer membrane proteins (OMPs) of the sensitive or resistant Pseudomonas aeruginosa strains, the OMPs were separated from the cellular elements by sarcosyl extraction method. OMPs profiles were conducted by SDSpolyacrylamide gel electrophoresis. Amoxicillin clavulanic acid (AMC) sensitive P. aeruginosa serotype K showed four protein bands; 35.713, 31.159, 26.107 and 22.869 KD. While AMC sensitive P. aeruginosa serotype H showed three bands of 35.713, 27.164 and 23.174 KD. Whereas AMC resistant P. aeruginosa serotype G, that was positive for the blaTEM gene by the PCR, modified its protein pattern. It has five protein bands of 52.142, 38.525, 30.690, 27.164 and 22.569 KD. These findings suggested that blaTEM gene and the outer membrane protein barrier are contributed to the resistance to amoxicillin clavulanic acid in P. aeruginosa. To determine a possible relationship between the resistance of P. aeruginosa and the production of antibodies against its outer membrane protein, antibodies against OMPs of AMC sensitive and resistant P. aeruginosa strains were prepared in mice and evaluated by ELISA. Our results showed that there was no association between immunogenicity of the outer membrane proteins and resistance of P. aeruginosa to antibiotics.