There is increasing interest in the use of higher levels of cereals in dairy cow rations. This reflects both die greater emphasis on milk protein concentration in milk pricing systems and the prospect of reductions in cereal prices as a result of reform of the Common Agricultural Policy. However, excessive processing of cereal grains results in rapid fermentation in the rumen which can lead to depressions in rumen pH and reductions in cellulose digestion and forage intake, particularly at high levels of feeding. Orskov et al (1978) have shown that treatment of whole cereal grain with sodium hydroxide (NaOH) reduced the rate of grain digestion in die rumen and enabled a higher forage intake compared to a similar level of ground cereal grain. However, inclusion of NaOH treated grain in die ration offered to dairy cows has produced varying effects on animal performance. The aim of the current study was to examine the effects of method of grain treatment on die performance of dairy cows offered a grass silage based diet and a range of concentrate intakes.