Forty-seven subjects were studied to discover predisposing factors for their radiologically diagnosed metatarsal stress fractures. Biomechanics of the foot and ankle were introduced to help explain forefoot varus, abnormal rearfoot valgus, and dorsiflexion as intervening variables in metatarsal stress fracture development. Results concluded that subjects with forefoot varus and decreased dorsiflexion had 8.3: 1 and 4.6: 1, respectively, odds of developing a metatarsal stress fracture. Abnormal rearfoot valgus had no significant effect on predisposing the subjects to develop a stress fracture. J Orthop Sports Phys Ther 1985;7(3):96-101.