2-Ethylhexanoic acid (EHA) was evaluated for acute toxicity to female Fischer F-344 rats (4/group) exposed to single oral doses of 0, 100, 800, 1600, or 3200 mg/kg of EHA administered in corn oil by gavage. Animals were observed for 14 days prior to necropsy. Mortality (4/4) occurred within 24 hours at the high- dose. Transitory weakness was observed in lower-dose animals. The acute oral LD50 for rats was 2043 (1445 to 2890) mg/kg. Preliminary data summaries of the following studies are presented: 1) A dermal irritation test with female rats exposed for 96 hours to 1 g/kg of undiluted EHA under occlusion; serious damage was seen in epidermal tissues within 24 hours. 2) Pharmacokinetic studies with rats orally exposed to 0.1 or 1.0 g/kg by gavage; urinary excretion accounted for 80% of each dose by 96 hours post- treatment, while fecal excretion accounted for about 12% of the low dose and 6% of the high-dose. Several metabolites were separated, but not identified. 3) 14-Day oral toxicity probe studies with mice and rats exposed to 0, 200, 800, or 1600 mg/kg/day EHA by gavage; 1600 mg/kg/day was lethal to rats, and 800 mg/kg/day led to decreased weight gain in males and increased liver weights in both sexes. In mice, there were slight changes in liver weights of high-dose animals. The NOAEL for mice was 800 mg/kg/day, and for rats, 200 mg/kg/day.