Addiction is a major problem of society. The existing evidences have shown that parental addiction impairs CNS development, learning, and memory. With respect to the role of glutamate in dentate gyrus on learning and memory, in this study, the effect of parental addiction to morphine on extracellular glutamate concentration in dentate gyrus was evaluated. For this purpose, male and female rats were addicted following 5-days oral administration of morphine (s.c.) and subsequently exposed to non-addicted female and male rats respectively. Basal and perforant path electrical stimulating glutamate concentration in the dialysate from dentate gyrus was measured. The results showed that the extracellular basal and stimulated glutamate concentration decreases in both female- and male-addicted groups. The concentrations were lower in mother-addicted female offspring than male offspring. These results suggest that parental addiction may cause learning and memory deficits. Therefore, general attention should be paid to this issue.