Acute oral toxicity was evaluated in groups of 10 male Wistar rats administered single doses of 98% pseudocumene by oral gavage at levels of 3.51, 5.0, 7.12 and 10.14 g/kg of body weight. Mortality was observed in 3 animals in the 5.0 g/kg dose group, 7 in the 7.12 g/kg dose group, and all 10 in the highest dose group. The LD50 value was calculated to be 6.0 g/kg of body weight, with confidence limits of 4.92 - 7.32 g/kg, by the Litchfield and Wilcoxon method. Clinical observations included lethargy, ptosis, ataxia, and piloerection. Gross necropsy findings were not reported.