Using a television-based vital microscopy method and immunohystochemical analysis, we have assessed the effect of intracerebral transplantation of syngeneic mesenchymal stem cells (MSC) on the brain cortex structure and the microcirculation in the pia mater of old rats. Using "open field" system, we have studied the effect of MSC transplantation on position-finding and discovery behavior of older animals. We have found that density of microvascular network of the pia mater increased ca. 1.9-fold in MSC recipients, compared to age-matched intact animals. Density of the arteriolar area of microvascular network of the pia mater increased ca. 2-fold. Reactivity of the newly formed arterioles was nearly equal to that of native microvessels. Intracerebral transplantation procedure itself was traumatic for brain cortex of rats, but it had no effect on the microcirculation in the contralateral hemisphere. Intracerebral transplantation of MSC did not improve locomotor behavi- or and emotional stage of old rats, did not increase their position-finding and discovery activity.