This report presents the results of experiments involving administration of the herbicide Trifluralin, dissolved in corn oil, delivered at different concentrations for each dose, either by intragastric intubation or intraperitoneal injection. The investigations produced several surprising results. These included the fact that, in per ora administration there were clear cut differences in toxicity such that for each dose which did cause death, there was inverse relationship between toxicity and concentration. This relationship was not seen in the intraperitoneal treatment groups. Further, there was no apparent difference in LD-50 in the two routes, and the time to death was greater in the intraperitoneally treated animals.