To optimize the immunological efficacy of CFC-101, an outer-membrane protein vaccine purified from relatively less pathogenic 4 different Pseudomonas aeruginosa strains, we investigated to establish its dose, administration route, interval and frequency of vaccination in mice. As expected, the 4 CFC-101 producing strains were less pathogenic than the challenging organism, P. aeruginosa GN11189. CFC-101 completely protected the death caused by P. aeruginosa at above 0.05 mg/kg vaccinized by 3 times with 7-day intervals. At the optimally effective dose of 0.2 mg/kg of CFC-101, at least 3 immunizations were necessary for complete protection against P. aeruginosa-induced death. If immunized 3 times, the immunization interval could be shortened up to 2 days to acquire the best protection against P. aeruginosa. CFC-101 was effective either by intraperitoneal, subcutaneous or intramuscular but not by oral administration. The present results show that the newly developed Pseudomonas vaccine, CFC-101, is highly effective for the protection from death caused by pseudomonal infections.