During the last few years, female competitive activity has increased dramatically. With this increase there has also been an increase in menstrual disorders in the female athlete. Menstrual cycle disorders include a delay in the onset of menses, failure to menstruate, and failure to ovulate. The most common is failure to menstruate. This occurs in 15% to 60% of exercising women. Often called athletic amenorrhea, it has many causes, including vigorous exercise, low body weight, and psychological and physical stress. This condition is also associated with loss of bone mass, premature osteoporosis, and increased risk of injury.