The cerebral glutamate system and NMDA-mediated glutamate transmission are known to play main roles in processes related to cognitive skills and emotional responses. The impact of the physical environment on emotional responses and the role of NMDA-mediated glutamate transmission in this interaction remain unknown. The present study aimed to investigate the role of NMDA receptors during the last maturation period of the nervous system in the effect of physical environmental conditions on anxiety responses induced by change (novelty), open field and height in adulthood. NMDA receptor blockade performed between postnatal 20-30 days with MK-801 treatment. Starting from postnatal day 20, rats were subcutaneously injected with MK-801 twice a day at the nape of the neck for a period of 10 days (dizocilpine either at a dose of 0.25 mg/kg or in a volume of 0.1 mL/20 g body weight). The open field apparatus and elevated plus maze were used to evaluate anxiety related behaviours in adulthood. In conclusion, enriched physical environmental conditions eliminated the anxiolytic effects of NMDA receptor blockade observed in rats reared under standard physical environmental conditions.