There have been a few studies that examined the oxidative stress effects of nicotine during pregnancy and lactation. We aimed to determine the adverse effects of maternal nicotine exposure during pregnancy and lactation on oxidant-antioxidant system, and to determine a protective effect of ascorbic acid (Asc). Gravid rats were assigned into four groups. In Group 1, pregnant rats received 6-mg/kg/day nicotine subcutaneously during pregnancy from 1 to 21 days of gestation and lactation (until postnatal day 21). Group 2 received nicotine and Asc for the same period. In Group 3, the rats received nicotine during lactation. Control pregnant rats (Group 4) received only saline subcutaneously. Serum malondialdehyde (MDA), myeloperoxidase (MTO), and superoxide dismutase (SOD) levels were determined at 21 days of age. Nicotine exposure decreased birth weight and pregnancy weight gain. MDA values of the rat pups exposed to nicotine in both Groups 1 and 2 were higher than those of control and Group 3. SOD and MPO values of the groups were similar. Mean birth weight and serum MDA levels of Groups 1 and 2 were similar. Nicotine exposure via placental transfer increases oxidative stress as manifested by an increase in MDA level. Asc supplementation does not prevent the adverse effects of maternal nicotine exposure.