The effectiveness of a commercially produced prill formulation in enhancing the Se level in a Se deficient grass/clover sward has been assessed. The product which contained 1% Se on a pressure impregnated mineral base was applied in early spring at two levels: 10g Se/ha (the recommended level) and 30g Se/ha. The Se levels in the herbage were subsequently monitored on cut samples taken over a 2 year period. The effect of N fertilisation on the Se status was also investigated.