AbstractA gene for ethionine resistance isolated from the yeast Saccharomyces cerevisiae DKD‐5D‐H conferred on the yeast cells resistance to seleno‐L‐methionine and capability to produce S‐adenosyl‐L‐methionine in the cells. An enzymatic study of the L‐methionine synthetic pathway of L‐methionine proto‐ and auxotrophs and in dried yeast cells with or without the gene suggested that the cloned gene for ethionine resistance is responsible for the activity of S‐adenosyl‐L‐methionine synthase. To produce S‐adenosyl‐L‐methionine by yeast cells transformed with the ethionine resistance gene, some culturing conditions were determined.