The insecticide Spinosad was administered by gavage to pregnant CD(R) rats at 0, 10, 50 or 200 mg/kg/day on gestation days (gd) 6-15 and to New Zealand White rabbits at 0, 2.5, 10 or 50 mg/kg/day on gd-7-19. Rats and rabbits were monitored for clinical signs of toxicity and body weight gains. At gd-21 (rats) or gd-28 (rabbits), maternal organ weights, reproductive parameters, fetal body weights, and fetal external, visceral and skeletal structures were evaluated. Rats given 200 mg/kg/day exhibited a 4% lower body weight on gd-12 and decreased body weight gains on gd-6-16 relative to controls. There was no maternal toxicity at 10 or 50 mg/kg/day, and no developmental toxicity in rats at any dose level. Rabbits given 50 mg/kg/day exhibited decreased feed consumption, reduced fecal output, body weight loss during the initial dosing period (gd-7-10) and a non-statistically significant decrease (31%) in body weight gain during the dosing period (gd-7-20). Two litters aborted due to maternal inanition. There were no maternal effects at lower doses, and no signs of developmental toxicity at any dose. Thus, the maternal no-observed-effect levels (NOEL) were 50 and 10 mg/kg/day in rats and rabbits, respectively, and the embryonal/fetal NOELs were 200 mg/kg/day in rats and 50 mg/kg/day in rabbits.