In the range finding study, groups of 5 male and 5 female F344 rats were fed DODP in the diet at levels of 0(control),0.1, 0.3 and 1.0% for 14 days. The rats were weighed before treatment, on the first day of treatment and thereafter twice weekly until necropsy. After an overnight fast, the animals were sacrificed and the weights of liver, kidneys and testes recorded. The livers from each animal were biochemically analysed for cyanide-insensitive palmitoyl-CoA oxidation and protein concentration. The results from this study were such that they indicated that the dose levels selected should be repeated in the 90-day feeding and 28-day peroxisome proliferation study.