Medial collateral ligament (MCL) injuries of the elbow in throwing athletes are part of a spectrum of valgus extension overload injuries. Clinicians should consider reconstruction of the injured MCL in those patients who are unable to return to sports activities or work after an interval of rest and rehabilitation. Surgical treatment of this disorder has continued to evolve from the original technique developed by Jobe and associates. The authors' surgical technique involves reconstruction of the MCL using a single ulnar tunnel and single humeral tunnel that is performed through a muscle-splitting approach that usually obviates the need for ulnar nerve transposition. Knowledge of the biology and biomechanics of MCL function is important in the diagnosis and treatment of MCL injuries of the elbow in the throwing athlete.