Overuse injuries are common in recreational and competitive sports as well as in day-to-day activities. The musculotendinous unit comprises the tissue most frequently involved: structural damage to the tendon occurs from repetitive strain and loading, from either endurance or skill activities that require technique and power. The potential for injury is enhanced by a great variety of predisposing intrinsic or extrinsic factors. Tendinous tissue will become fatigued as its basal reparative ability is overwhelmed by repetitive dysfunctional and microtraumatic processes. Tendinitis is the earliest recognisable manifestation of overuse injury: as damage progresses, partial tears and complete ruptures may ensue. The diagnosis of overuse injury rests with identification not only of the affected tendinous unit, but also of the underlying predisposing condition or conditions. Treatment can then proceed with elimination or correction, if possible, of these conditions, together with control of inflammation and programmes of modalities designed to restore the structural and functional integrity of the tendon. Knowledge of overuse problems has grown exponentially in the past 3 decades, as evidenced by the outpouring of scientific and medical literature. Sophisticated analytical techniques, supplementing a sound history and physical examination, have greatly facilitated the diagnosis of overuse problems and allowed the application of scientific therapeutic principles. As the number of participants in recreational activities continues to grow, the application of these techniques in ever more innovative ways holds the greatest promise for the prevention of overuse tendon injuries.