While the milk yield response of spring calving dairy cows to concentrate supplementation during the main summer grazing period has been examined in a number of studies, there is little information available concerning the milk yield response to supplementation in late summer/early autumn. With milk yield at this stage of the lactation having declined considerably, supplementation might appear unnecessary. However, herbage quality and availability are also lower in late season, and as such, responses to concentrate supplementation might be expected. This study was conducted to examine the milk yield response to concentrate supplementation of dairy cows grazing late summer/autumn grass.