In this study, we demonstrated several mechanisms exploring the inhibitory eAect of low-dose adenosine on lymphoma cell growth. Adenosine, a purine nucleoside present in plasma and other extracellular fluids, acts as a regulatory molecule, by binding to G-protein associated cell-surface receptors, A1, A2 and A3. Recently we showed that low-dose adenosine released by muscle cells, inhibits tumour cell growth and thus attributes to the rarity of muscle metastases. In the present work, a cytostatic eAect of adenosine on the proliferation of the Nb2-11C rat lymphoma cell line was demonstrated. This eAect was mediated through the induction of cell cycle arrest in the G0/G1 phase and by decreasing the telomeric signal in these cells. Adenosine was found to exert its antiproliferative eAect mainly through binding to its A3 receptor. The cytostatic anticancer activity, mediated through the A3 adenosine receptor, turns it into a potential target for the development of anticancer therapies. # 2000 Elsevier Science Ltd. All rights reserved.