Acute inhalation toxicity was evaluated in groups of 5 male and 5 female Sprague-Dawley albino rats exposed to dibutylamine at actual concentrations of 0.76, 1.08, 1.18, 1.39 or 3.91 mg/l of air for 4 hours. Mortality was observed in 2 animals in the 0.76 mg/l dose group, 4 in the 1.18 mg/l dose group, and all 10 in both the 1.39 and 3.91 mg/l dose groups. The LC50 value was calculated to be 1.15 mg/l (standard error of 0.095 mg/l) by the log probit method of Miller and Tainter. Clinical observations included excessive salivation, lacrimation, gasping, convulsions, abnormal breathing, ataxia, lethargy, rales, and staining of the urogenital area. Gross necropsy revealed lung congestion in decedents.