In the nervous system nucleotides and nucleosides have been shown to be involved in a myriad of important physiological processes, including the regulation of trophic effects (proliferation and differentiation) on neurons and glial cells. Here we functionally characterized the purinergic system of the anterior telencephalon of larval Xenopus laevis using Ca²⁺ imaging and immunohistochemical techniques. Like in other vertebrates, the anterior part of the telencephalon of our experimental animal mainly consists of the olfactory bulb (OB), the first relay center of the olfactory system. In Xenopus the lateral telencephalic ventricles expand deeply into the anterior telencephalon. Therefore, the periventricular zone (PVZ), known to contain proliferating neuronal stem cells, is in close contact with the OB. We found that varying purinergic receptor subtypes are expressed in cells of this brain area, and that application of purinergic agonists initiates stereotypic [Ca²⁺]_i signaling. While in cells of the OB these responses were completely abolished in absence of extracellular Ca²⁺, in cells of the PVZ a residual response persisted. The responses were substantially reduced by known purinergic antagonists. The order of potency of several purinergic agonists consistently differed in the two cell types. Taken together, our findings show that the anterior telencephalon features a complex purinergic system. While cells of the OB exclusively express P2X receptor subtypes, cells of the PVZ express P1, P2X as well as P2Y subtypes. Regarding the purinergic receptors expressed in the OB we could show that they are not involved in the processing of olfactory information. Possible implications of the purinergic signaling in the context of cell proliferation in the PVZ and cell turnover in the OB are discussed. [Supported by grants from the Research program, Faculty of Medicine, Georg-August-University Göttingen to I.M., and the DFG CMPB (Project B1/9) to I.M. and D.S.]