Studies in humans and animal models (including rodents) have revealed lasting behavioral and cognitive impairments in offspring prenatally exposed to nicotine. Offspring of pregnant mouse dams prenatally subjected to 9-10 daily subcutaneous injections into the nape of the neck during pregnancy have been postnatally subjected to several developmental and behavioral tests to investigate the effects of prenatal nicotine exposure on those offspring at various stages of their life. The prenatal exposure to nicotine has resulted in significant reduced postnatal body weight gain, as well as in significant delay in eye opening, in the appearance of body hairs, and in sensory motor reflexes. However, motor activity was significantly stimulated in early adulthood of mouse pups prenatally exposed to nicotine, and such exposure proved to have long-lasting hyperactive effects on mice. Thus, exposure to nicotine during a critical prenatal period of brain development deduced from the present study in mice raises the alarm of the possible hazard of prenatal exposure to nicotine in humans. Hence, smoking by pregnant women might constitute a serious hazard to their in utero developing children.