The present volume is the third volume of a projected four-volume series. This volume contains the following chapters: .The Synthesis and Reactions of Pyrrole, Pyrazole, Triazole, Indole, Indazole, and Benzotriazole Nucleosides and Nucleotides, The Synthesis, Reactions, and Properties of the 2'(3')-O-Aminoacyl and Peptidyl Nucleosides and Nucleotides, Syntheses and Reactions of Bicyclic Heterocyclic Nucleosides and Nucleotides, The Synthesis and Chemistry of Imidazole and Benzimidazole Nucleosides and Nucleotides, and The Chemistry of C-Nucleosides. Each chapter is comprehensive in nature and should provide a ready reference source for not only the novice but also the experienced investiga tor or researcher. The chapters have been prepared by authors with considerable experience in each particular area of research, and this has resulted in a lucid presentation of each well-defined area. These volumes (1-3) were designed with medicinal chemists, medicinal organic chemists, organic chemists, carbohydrate chemists, physical chemists, and biological chemists in mind. However, because of the tremendous recent interest in this research area owing to the biological and chemotherapeutic evaluation ofnucleosides and nucleotides as anticancer, antiviral, and antiparasitic agents, these volumes should also be valuable additions to the libraries of virologists, biochemical phar macologists, oncologists, and pharmacologists. We would like to thank the authors for their enthusiasm and help in making these volumes available to the scientific community.