We report herein an efficient synthesis of 4-substituted triazolyl-nucleosides and their in vitro cytostatic activity. The synthesis is based on a straightforward 1,3-dipolar cycloaddition between 1-azido-ribose 2 and terminal alkynes under a cooperative effect of microwave activation and copper (I) catalysis. All cycloadducts were obtained in nearly quantitative yield after a short reaction time (1 to 2min). After removal of acetyl protecting groups, the free nucleosides were evaluated against L1210, Molt4/C8, and CEM tumor cell lines. Structure-activity relationship study shows that the substituent on the triazole ring has a major effect since nucleosides 4c and 4g, containing, respectively, a long alkyl chain and an aryl donor group are the most active compounds in this series.