Abstract: Members of the RNA-helicase family are defined by several evolutionary conserved motifs. They are found in all organisms - from bacteria to humans - and many viruses. The minimum number of RNA helicases present within a eukaryotic cell can be predicted from the complete sequence of the Saccharomyces cerevisiae genome. Recent progress in the functional analysis of various family members has given new insights into, and confirmed the significance of these proteins for, most cellular RNA metabolic processes.