This study examines possible interactions between behavioral effects and influence of N-methyl-D-aspartate acid (NMDA) receptors in 4 and 12-week streptozotocin (STZ) induced diabetic rats. Effects of NMDA receptor agonist on spatial learning were tested in control groups of rats and in rats with 4 and 12 weeks diabetes mellitus (DM). Experimental diabetes was induced by a single intravenous injection of streptozotocin at a dose of 65 mg/kg, dissolved in citrate buffer. We used the water maze task and examined the acquisition and the retrieval of spatial memory in rats. In our present experiments, we observed that DM had no significant influence on acquisition and retrieval in 4 week diabetic rats on Morris water maze, but impaired examined parameters in 12 week diabetic rats in this test. The NMDA receptor agonist did not influence acquisition but increased recall on water maze in 12 week streptozotocin diabetic rats.