Calcific tendinitis is a common condition where calcium deposits form in a tendon, sometimes causing pain at the affected site. Deposits can occur in several places in the body, but are by far most common in the rotator cuff of the shoulder. Around 80% of those with deposits experience symptoms, typically chronic pain during certain shoulder movements, or sharp acute pain that worsens at night. Calcific tendinitis is typically diagnosed by physical exam and X-ray imaging. The disease often resolves completely on its own, but is typically treated with non-steroidal anti-inflammatory drugs to relieve pain, rest and physical therapy to promote healing, and in some cases various procedures to breakdown and/or remove the calcium deposits.

Adults aged 30–50 are most commonly affected by calcific tendinitis. It is twice as common in women as men, and is not associated with exercise. Calcifications in the rotator cuff were first described by Ernest Codman in 1934. The name, "calcifying tendinitis" was coined by Henry Plenk in 1952.