Wrist tendonitis is a condition in which the tendon or tendon sheath becomes irritated and inflamed resulting in a painful condition. This is an overuse injury most commonly caused by a rapid increase in activity or change in activity with poor mechanics. The two most common types of tendonitis involve tendons near the base of the thumb or on the ulnar side (the side of the wrist at the base of the ring finger and small finger). Most patients will complain of sharp pain with sudden movements. The most common type is called De Quervain’s tenosynovitis and this produces symptoms of sharp pain in the wrist at the base of the thumb. Most are successfully treated with corticosteroid injection into the tendon sheath, activity modification, and splinting. If left untreated, the condition can cause restrictive scarring of the tendon sheath. Refractory cases require release of the tendon sheath surgically which is done as a relatively short outpatient procedure.