Studies of changes in the numbers and some morphometric parameters of neurons and gliocytes in the mesoaccumbocingulate (MAC) dopaminergic system in rats were performed using pre- and postnatal exposure of this system to opiates, i.e., 0.1 mg as 1% morphine hydrochloride solution into the amnion of fetuses of female Wistar rats (n = 4) on post-fertilization day 17 or i.p. to rat pups on postnatal day 4 (n = 4). Perinatal exposure to morphine induced chromophilic degeneration, swelling, and the death of some neurons, along with decreases in the volumes of other (less damaged) neurons in the MAC system of rats. Neuron damage, more marked after prenatal administration, was accompanied by an increase in the number of microgliocytes and their phagocytic activity. Morphine did not alter the number of satellite macrogliocytes or the mean distance from these cells to the bodies of less damaged neurons.