N-butyl acrylate (CAS No. 141-32-3) was evaluated for developmental toxicity. It was administered to groups of 15 fertilized female rats per group dosed with 0, 25, 135, and 250 ppm for 6 hours per day by inhalation on days 6-15 of gestation. Body weight gain was reduced by 95% at 135 ppm or above. There were no deaths in any of the test groups. Conception rate, corpora lutea, or weight of placentas were not affected by treatment. The percent of live implants per pregnant rat were reduced by 95% relative to controls. The number of dead implants per pregnant rat was increased in comparison to controls (significance 99%). The number of early resorptions increased at 135 ppm or above (statistical significance was not reported). Medium-late resorptions were increased in all test groups (statistical significance was not reported). No late resorptions were observed in any of the test groups. The percentage of dead implants per pregnant rat was increased by 99% relative to controls. The weight of male fetuses was increased by 95% relative to controls. The weight of female fetuses was not altered by treatment. The length of the fetuses was larger on the average by 99% at 25 ppm or above. Anomalies, variations and/or retardations observed in treatment groups were not different from controls. It was concluded that the toxic dose was between 25 and 135 ppm.