'Premature' rats that were delivered by cesarean section on day 21 of gestation and 'normal' rats that were delivered spontaneously on day 22 of gestation were tested for basal locomotor activity and locomotor stimulation in response to D-amphetamine at 19-21 days of age. Compared to normal rats, premature rats had increased basal levels of locomotor activity and showed enhanced sensitivity to the locomotor stimulant effects of D-amphetamine. Cesarean-delivered premature rats may be a useful animal model for investigating mechanisms of neurobehavioral deficits associated with premature birth in humans.