In briefA 16-year-old cross-country runner and Nordic skier presented for a preparticipation examination with primary amenorrhea and a 3-month history of right fourth metatarsal stress fracture. The history and physical exam narrowed the cause to a hypothalamic disorder; inadequate nutrition might have played a role. The stress fracture resolved after 2 months of oral contraceptive use. The case illustrates the multifactorial nature of amenorrhea and the need for an individualized approach to diagnosis and treatment.