Growth of the yeast Saccharomyces cerevisiae was unaffected by up to 24 h exposure to ethanol concentrations ranging from 1% to 9%, but was reduced following exposure to 12% ethanol. Concentrations of the polyamines putrescine, cadaverine and spermidine were not affected by a 24 h exposure to 12% ethanol, although there was a significant increase in spermine level. These changes were accompanied by significant increases in the activities of the polyamine biosynthetic enzymes ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) and in the flux of label from ornithine into the polyamines. Formation of the cadaverine derivatives aminopropylcadaverine and N,N-bis(3-aminopropyl)cadaverine was greatly increased in yeast exposed to 12% ethanol for 24 h, probably via the action of ODC, AdoMetDC and the aminopropyltransferases. Exposure to 12% ethanol also led to substantial reductions in the uptake of putrescine and spermidine and the amino acid methionine.