Recent studies have identified a new family of desaturase-like polypeptide sequences in many higher eukaryotes. Functional characterisation of one member of this family, from Schizosaccharomyces pombe, revealed the enzyme to be a sphingolipid desaturase. This S. pombe gene designated SDCB3b8.07c was identified as the dihydroceramide Delta(4)-desaturase, responsible for the synthesis of sphingosine. Homologous recombination was used to disrupt the endogenous S. pombe dihydroceramide Delta(4)-desaturase. Surprisingly, this had no effect on cell viability, indicating that sphingosine may not be crucial for normal S. pombe functions. This observation has implications for our understanding of the role of sphingosine and its phosphorylated metabolite sphingosine-1-phosphate in lower eukaryotes.