The effect of treatment with tetracycline, streptomycin, or chloramphenicol on mortality and wound healing patterns of irradiated and nonirradiated rats was assessed. The administration of tetracycline and streptomycin diminished the mortality in combined radiation and surgical injury; chloramphenicol, streptomycin, or tetracycline did not change the normal wound healing pattern in nonirradiated animals, nor did the administration of these antimicrobials restore the wound healing pattern in the irradiated animal to normal. These data suggest that infection may not play a primary role in the delay in wound contraction attendant to radiation injury.