During two grazing seasons (May–September 1972 and 1973), the relationship between the dry matter intake of dairy cows on a Lolium Cynosuretum (grass-legume) pasture and the digestibility of the herbage was studied. Herbage intake was determined by cutting representative samples, and the apparent digestibility of the daily herbage allowance was assayed in conventional digestion trials. 1. (i) The digestibility of the herbage, as average coefficients for both grazing seasons, was as follows: organic matter 73%, crude protein 75%, ether extract 52%, crude fibre 76% and N-free extract 72%. The results, however, indicate that under practical grazing conditions large variations are encountered. 2. (ii) From the first to the fifth regrowth of the herbage the digestibility decreased, on the average by 8–10 percentage units and varied within the range of 70–80% for the organic matter, crude protein and crude fibre. 3. (iii) The daily consumption of herbage offered ad libitum averaged 11.8 kg dry matter per cow with a relatively large variation, and was positively correlated with the herbage allowance ( P < 0.001) and the digestion coefficient of the organic matter ( P < 0.05). A multiple regression equation relating intake to these two independent variables accounted for 66% of the variation of the dry matter intake by the dairy cows on pasture ( P < 0.001). The partial regression coefficient indicates that the herbage intake increases by 0.55 kg dry matter with each per cent increment in the digestibility of the organic matter over the range 64–80%. The digestibility of the ether extract had a small negative, though statistically significant, association with herbage intake. There was no significant correlation between herbage intake and the digestibility of crude protein, crude fibre and N-free extract.