A total of 34 samples from ear, blood, sputum, burns, CSF and cystic fibrosis infections were collected from Al-No'man hospital, Central Medicine City hospital and from sewage of Al-Dorra in Baghdad governorate. From these samples we got 18 isolates, 12 were identified to belong to Pseudomonas spp. according to their ability to grow on ceteremide agar. These isolates were subjected to biochemical, morphological and physiological tests and as a result, 6 of them were Pseudomonas aeruginosa and it has been proved using API 20E system. The ability of local isolates of Pseudomonas aeruginosa for lectin production and haemagglutination of RBCs for human blood groups (A, B, O) and sheep RBCs were studied, results showed that all these isolates has a high ability for haemagglutination of different RBCs. The ability of the locally isolated Pseudomonas aeruginosa S4 for lectin production was studied and it was producing for both types of lectins (PA-IL and PA-IIL), lectins were purified using precipitation by ammonium sulfate then dialyzed and eluted using gel filtration by sepharose-200 CL-6B. the same technique (gel filtration) has been used for molecular weight determination for both types of lectins by using standard proteins with known molecular weight (lysozyme, BSA and choline esterase). Results showed that the molecular weight of PA-IL approximately was 57500Da while for PA-IIL approximately was 42700Da. Also the ability of antibiotic resistance for Pseudomonas aeruginosa S4 was studied for different antibiotics and it was resistant to vancomycin, chloramphenicol, carbenicillin, cefotaxime, cephalexin, tetracycline and bacitracin. The effect of physical mutagen (using UV light) and chemical mutagen (using mitomycin C) on the ability of Pseudomonas aeruginosa S4 for lectin production were studied also. Results showed that physical mutagen was more effective than chemical mutagen on the ability of this isolate for lectin production in which haemagglutination activity of RBCs for human blood groups (A, B, O) and sheep RBCs has been reduced by the bacterial mutants, in the same time we have got a bacterial mutants which has a high haemagglutination activity for different blood groups compared to that of the wild type of Pseudomonas aeruginosa S4.