The DED1 gene, which encodes a putative RNA helicase, has been implicated in nuclear pre-messenger RNA splicing in the yeast Saccharomyces cerevisiae. It is shown here by genetic and biochemical analysis that translation, rather than splicing, is severely impaired in two newly isolated ded1 conditional mutants, Preliminary evidence suggests that the protein Ded1p may be required for the initiation step of translation, as is the distinct DEAD-box protein, eukaryotic initiation factor 4A (eIF4A), The DED1 gene could be functionally replaced by a mouse homolog, PL10, which suggests that the function of Ded1p in translation is evolutionarily conserved.