Abstract: The purpose of introns in the architecturally simple genome of Saccharomyces cerevisiae is not well understood. To assay the functional relevance of introns, a series of computational analyses and several detailed deletion studies were completed on the intronic genes of Saccharomyces cerevisiae. Mining existing data from genome-wide studies on yeast, it was discovered that intron containing genes produce more RNA, more protein and are more likely to be haploinsufficient than non-intronic genes. These observations for all intronic genes held true for distinct subsets of genes including ribosomal, non-ribosomal, duplicated and non-duplicated. Corroborating the result of computational analyses, deletion of introns from three essential genes decreased cellular RNA levels and caused measurable growth defects. These data provide evidence that introns improve transcriptional and translational yield and are required for competitive growth of yeast.