The effect of hay supplementation on the performance of dairy cows on a restricted intake of paspalum-dominant perennial pasture was studied in two 21 -day periods in the eighth and ninth months of lactation. In each period, there were three groups fed pasture only at mean intakes of 15.2, 11.5 and 7.3 kg/cow day-1, two groups fed at similar pasture restriction levels and supplemented with hay ad libitum, and one further group fed an average of 7.3 kg of pasture supplemented with only 4.3 kg of hay. The data were analyzed by regression, using total dry matter intake as the dependent variable, and pseudovariables were used to examine the effects of hay feeding. The relations between total dry matter intake and milk, butterfat, protein and solids-not-fat production, and change in body condition of dairy cows were not altered by ration composition. Milk production declined linearly by 0.66 kg and 0.31 kg/cow day-1 in the eight and ninth months of lactation, respectively, for each kg reduction in total dry matter intake. Similar responses were obtained for butterfat, protein and solids-not-fat production. Gain in body condition of the cows also decreased as total intake fell, but the relation was curvilinear and not affected by stage of lactation. It was concluded that high quality hay can be used to overcome shortages of paspalum-dominant perennial pasture in autumn, and that it has similar. nutritive value to pasture in terms of milk production and body condition.