Toxicity of imbrimycin administered orally and its local irritating effect was studied experimentally. Imbrimycin was diluted with flagosol for decreasing its local irritating effect on the mucosa of the eye conjunctiva and vagina of rabbits. Administration of imbrimycin suspension to albino rats in doses of 10 and 50 mg/kg for 14 days had no effect on the body weight, liver antitoxic function and pathomorphological indices. Oral administration of the drug to dogs in a dose of 10 mg/kg caused a decrease in the body weight, vomiting and diarrhea, had no effect on the dog blood picture and induced no pathomorphological changes in the inner organs. The local irritating effect of imbrimycin was found to be equal to that of azalomycin F. Flagosol significantly decreased the irritating effect of imbrimycin on the eye conjunctiva and the vagina mucosa.