Leukopenia associated with silver sulfadiazine (SSD) is a frequent event and may be a risk factor for infectious complications in the burn patient. This study reviews 77 patients with thermal injuries to determine total body surface area (BSA) burned, and white blood cell count (WBC) at time of hospital admission. A subpopulation of 56 patients with serial WBC counts were evaluated to determine lowest WBC count, topical burn therapy, episodes of infection or septic shock and final outcome. There was not a significant incidence of leukopenia on admission. Fifty-six per cent of patients treated with SSD and 12 per cent of silver nitrate-treated patients became leukopenic (P less than .05). The leukopenia was higher among SSD-treated patients who had greater than 15 per cent BSA burns (P less than .05). The onset of leukopenia generally occurred the second day after the burn and the WBC count returned to normal with discontinuance of the drug. The leukopenia was due primarily to a marked decrease in the number of mature neutrophils. There was no difference in the incidence of septic complications or opportunistic infections in the treatment groups. There was no significant difference in final outcome. Silver sulfadiazine-induced leukopenia appears to be a self-limited phenomenon that does not increase the incidence of infectious complications nor affect final outcome.