The pathway of the maloalcoholic fermentation in Schizosaccharomyces pombe was investigated by a 1H-, 2H- and 13C-n.m.r.-spectroscopic study of hydrogen and deuterium distribution on the ethanol produced by S. pombe from L-malic acid in 2H2O and from L-[2-2H]malic acid. Our findings rule out a double-decarboxylation mechanism and agree with a pathway that involves acetaldehyde as intermediate.