R,R-Monatin is an intensely sweet substance originally identified in the root bark of Sclerochiton ilicifolius. R,R-Monatin salt, commonly known as "arruva", has potential for use as a high-potency sweetener food ingredient. Previously, arruva was concluded to present no toxicologically relevant effects to Crl:CD(SD) rats and Crl:CD-1(ICR) mice fed up to 35,000 ppm arruva in the diet for 90 days. In the present study, groups of mated Sprague-Dawley rats (25 Crl:CD(SD) females/group) were exposed continuously to 0 (control), 15,000, 30,000, or 50,000 ppm arruva in the diet during gestation days 6-21. There were no fetal malformations or developmental variations that were attributable to arruva at any exposure level, nor were there any test article-related effects on intrauterine survival. Maternal toxicity, evidenced by lower mean body weights, body weight gains and feed efficiency, was observed at 50,000 ppm. A developmental effect, in the form of lower mean fetal body weight, was noted in the 50,000 ppm group in the presence of maternal toxicity. Therefore, the dietary no-observed-adverse-effect level (NOAEL) for maternal and embryo/fetal developmental toxicity of arruva in pregnant rats during gestation days 6-21 was 30,000 ppm (equivalent to 2564 mg/kg bw/day) based on reductions in maternal and fetal body weights.