This chapter describes aspects of processing of precursors to tRNA, rRNA, and mRNA in yeast. In general, RNA processing in yeast appears to be similar to that of higher eukaryotes. Why, then, a separate chapter for yeast? The answer regards the distinct manner and ease in which much of the information regarding RNA processing in yeast has been obtained. This difference is due to the well-defined genetics which has allowed identification and characterization of many mutations which alter RNA substrates or products essential for the production of mature RNAs. Additionally, the well-defined genetics, in conjunction with the development of cloning technology and the yeast transformation system 1 and surrogate and in vitro transcription-processing systems, have aided the analysis of individual genes and their intermediate and mature RNA products. Hence, the intention of this review is to emphasize how the combination of genetic, recombinant DNA, and biochemical approaches have been used to study aspects of RNA processing in yeast. Only the processing of nuclear-encoded RNA species is considered. The description of steps involved in the production of mature nuclear-encoded RNAs has been restricted to those steps which occur after an initial precursor transcript has been generated and does not include any discussion of gene regulation, promotion or termination of transcription, or RNA turnover. Although most of the work described here is from studies of Saccharomyces cerevisiae, some studies of Schizosaccharomyces pombe and Saccharomyces carlsbergensis have been included where these contribute important additional or corroborative information. The reader is also directed to recent and excellent reviews by others discussing tRNA processing2,3 and rRNA processing 4 in yeast.