Two digestion-intake trials were conducted with 24 male and female white-tailed deer (Odocoileus virginianus) fawns during January, February, and March 1971. Within each trial deer were randomly assigned to one of six treatments representing a basal diet diluted with oak sawdust in levels of 0, 15, 25, 30, 35, and 45 percent. Dry matter (DM) digestibility and the digestible energy (DE) content (kcal DE/gram) were highly correlated with the percent dilution. Dry matter intake (grams/$\text{BW [kg body weight]}^{0.75}$/day) increased as digestibility decreased from a high of 3.44 kcal DE/gram to 2.17 kcal DE/gram; below this point intake decreased. Digestible energy intake (kcal $\text{DE/BW}^{0.75}$/day ± SE), on the other hand, remained relatively constant (155.2 ± 7.46) kcal above 2.17 kcal DE/gram. The data indicate that these animals were able to maintain a constant energy balance, close to the maintenance requirements of fawns, by adjusting dry matter intake when fed diets of medium to high digestibility (DE > 50 percent). Below 2.17 kcal DE/gram, energy intake decreased with the decrease in dry matter intake. The point (2.17 kcal DE/gram) representing the intersection of two regression lines for DM intake versus kcal DE/gram of feed was taken to be the threshold at which digestive tract fill began to limit the dry matter and energy intake of these animals. These results are discussed in terms of a theoretical model of the intake mechanism of ruminants.