White muscle disease appeared in lambs born of ewes in the zero grazing group during the course of a comparative fertility trial on ewes on various systems of husbandry. Analysis of the feed showed barely adequate selenium in the maize silage and a deficiency in the soil on which the high lysine maize was grown. Treatment of the lambs with a selenium/vitamin E injection rapidly controlled the condition. This deficiency may be more widespread than is presently realised.