Rodriguez, J. Instituto de Biologia, Universidad de Talca, Talca, ChileThe gastroprotective activity of the essential oil from the bark of Croton cajucara Benth (Euphorbiaceae) was assessed in three different models of experimentally induced gastric ulcer in mice. At oral dose of 100 mg/kg the essential oil reduced gastric lesions induced by hypothermic restraint stress and HCl/ethanol significantly. In the HCl/ethanol model a dose-dependent gastroprotective effect was found. Moreover, significant changes in gastric parameters such as pH, secretion rate and total gastric acid were found after intraduodenal administration of essential oil under ligated pylorus (Shay) conditions. The acute toxicity of essential oil was assessed in mice. The LD50 values were 9.3 and 680 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of essential oil was studied also. A dose-dependent cell viability inhibition was found in V79 fibroblast cell cultures with an IC50 of 22.9 μg/ml. Our results support the pharmacological study of this essential oil.