Iminodiacetic acid (142-73-4) was evaluated for developmental effects in groups of 6 female Charles River rats administered the test substance by gavage at dose levels of 0, 500, 2000, 2000, 3000, or 4000 mg/kg/day on days 6 through 15 of gestation. All animals in the 3000 and 4000 mg/kg/day groups died and 5 of 6 died at 2000 mg/kg/day. Clinical signs in the three highest dose groups included respiratory difficulty, lowered body temperature, and hypoactivity. Necropsy of rats at the three highest doses revealed hemorrhages of the stomach, pronounced blood vessels in the intestines, and dark red renal medullae and adrenal cortices. Rats at 1000 mg/kg/day showed reduced body weights during day 6 through 10 of gestation. No signs of maternal toxicity were observed in the 500 mg/kg/day group. There were no treatment related reproductive effects or fetal abnormalities observed. No statistical analysis was performed due to the low number of test animals.