Abstract Pronase hydrolysates of crude gluten preparations from naturally seleniferous wheat seeds were subjected to ion-exchange chromatography and the eluates were examined chemically for selenium. Almost half of the selenium in the hydrolysate was accounted for as selenomethionine, but selenocystine was not detected. More detailed studies were then made on wheat gluten, seeds and straw from plants grown on soil to which 75Se-selenate had been added. On pronase hydrolysis of the seeds or the gluten, about half of the selenium could again be accounted for as selenomethionine. On examining protein-free, hot-water extracts of the seeds or straw of these plants, no free selenomethionine could be detected, suggesting the rapid incorporation of this amino acid into protein. Neither selenocystine, the seleno-half-cystine moiety nor Se-methylselenocysteine was detected in the hydrolysates or in the water extracts. The results suggest, however, the presence of selenocysteic acid in significant amounts in the gluten, the seeds and the straw. Over half of the selenium in the straw could be accounted for as selenate, but selenite was not found. Selenium compounds eluted shortly after selenite, selenate and cysteic acid, suggesting the presence of oxides of selenomethionine.