INTRODUCTION: Adult hippocampal neurogenesis occurs in many mammalian species, including the laboratory opossum (Monodelphis domestica). Newborn neurons in the dentate gyrus (DG) of the hippocampal formation are involved in learning and spatial memory.The rate of neurogenesis decreases with aging, which was suggested as the cause of the deterioration of cognitive functions. AIM(S): The aim of the study was to examine association between adult neurogenesis in the DG and spatial memory in young and aged opossums METHOD(S): To understand whether new neurons contribute to learning and memory, we performed experiments on young and aged laboratory opossums using the Morris water maze test in which animals learn to locate the hidden platform. After behavioral test, sections from opossum brains were immunostained with doublecortin – a marker of newly born neurons – to investigate the rate of adult neurogenesis in the DG. RESULTS: In the group of young opossums, the time required to find the hidden platform was already significantly lower on the third day of training (vs. day 1, p<0.005), while in aged opossums a significant difference was observed on the fourth day of training (vs. day 1, p<0.02). The level of neurogenesis in the DG of the hippocampal formation was lower in the aged opossums than in the young animals. CONCLUSIONS: However, even the low number of newly formed neurons in the DG of aged opossums are likely to be involved in the formation of spatial memory. FINANCIAL SUPPORT: This research was supported by the National Science Centre Poland, grant number 2015/17/B/NZ4/02410.