The effects of nutrition on the incidence of stress fractures among classical ballet dancers were studied. Ten dancers with stress fractures were compared with a group of dancers without stress fractures and a group of nondancing control subjects. Subject pairs were matched for age, weight, and height. Specific nutrient intake and eating patterns were thus isolated to determine if dietary patterns could account for the incidence of stress fractures among these dancers. The majority (80%) of the 10 dancers with recent stress fractures had weights less than 75% of ideal (p less than 0.05) and showed a greater incidence of eating disorders (p less than 0.05). This group also showed a lower fat intake and a higher intake of low-calorie food (p less than 0.05). Menstrual patterns and bone density studies of the wrist, foot, and spine did not differ among the three groups, showing that stress fractures were significantly associated with a more-restrictive diet.