Stress fractures are common injuries in sports medicine clinics. The few reported cases of stress fractures of the metacarpal bones have been associated with overuse, athletic or occupational techniques, and equipment problems. We describe a stress fracture of the index metacarpal in an adolescent tennis player. An increase in training intensity, combined with a recent change in stroke biomechanics and racket grip, were thought to be predisposing factors for this fracture. A similar mechanism and location of injury has been previously described, suggesting a common mechanism. Relative rest, a change in racket grip, and appropriate physical therapy facilitated a quick return to asymptomatic tennis. A brief review of metacarpal stress fractures is presented.