CFC-101, a Pseudomonas vaccine, was administered to beagle dogs by intramuscular injection for 4 weeks (5 days/week) at 0.05, 0.15 and 0.45 mg/kg/d. Clinical signs considered to be related to treatment were restricted to swelling at the injection sites, being apparent 1-2 h after treatment. There was no effect on body weight, food consumption, ophthalmoscopy, electrocardiography, hematology, biochemical and urinary parameters. The histopathological examination revealed treatment-related changes at the injection sites at all dosages, particularly in the hindlimbs where both perivascular and intramuscular aggregations of inflammatory cells were seen. Thus, the only treatment-related changes seen in this study were local reactions to the test substance at the injection sites; furthermore these changes seem to represent a pharmacological response to the test material. Because no evidence of any systemic toxicity was observed at any dosage level, it is concluded that dosages of CFC-101 up to and including 0.45 mg/kg/d were well tolerated over a period of 4 weeks in the beagle dog.