We have studied the effect of relatively high concentrations of extracellular N-acetylaspartate (NAA) on the intracellular free calcium concentration [Ca2+](i) in NTera2-neurons, While low concentrations of extracellular NAA (0.1, 1 mM) had no effect on the [Ca2+](i), high concentrations of extracellular NAA (3, 10 mM) elicited sharp and statistically significant elevations of [Ca2+](i). Different classes of antagonists of the N-methyl-D-aspartate (NMDA) receptor abolished the NAA induced elevations of the [Ca2+](i), indicating the involvement of the NMDA receptor in NAA-induced elevations of [Ca2+](i).