A revision of the most recent advances on chemistry and biological activity of nucleoside analogues in which the furanose ring has been replaced by a different heterocyclic ring (heterocyclic nucleosides) is summarized. Encouraging results obtained by lamivudine, the flagship of that family of nucleoside analogues, has created great interest and focused attention on that sort of compounds. As a consequence, the synthesis of new generations of heterocyclic nucleosides flourished in hope of new drug discovery with improved pharmacokinetic properties. This review outlines essentially the recent progress in chemical methods directed to the preparation of the title compounds. Note. The name HETEROcyclic nucleosides is used by analogy to CARBOcyclic nucleosides (those in which the furanose ring has been replaced by a carbocyclic ring).