N6-(indol-3-yl)alkyl derivatives of adenosine were synthesized. The adenosinereceptor affinity and the antinociceptive activity of these compounds were assessed in binding studies and the phenylbenzoquinone-induced writhing test. Most of these analogues exhibited a potent analgesic activity without side effects. Among them, compound 3c (UP 202-32) bound to A1 (Ki = 110 nM) and A2 (Ki = 350 nM) adenosine receptors