This report documents the clinical, radiographic and histologic findings in a 46-year-old man with calcifying tendinitis in his left shoulder which progressed to rotator cuff tear. The patient had a 1-year history of repeated calcifying tendinitis before being referred to our hospital. On the initial visit, radiographs and magnetic resonance imaging (MRI) revealed calcium deposition localized in the supraspinatus tendon without apparent tear. Three months after the first visit, MRI revealed a partial-thickness rotator cuff tear at the site of calcium deposition. Surgical and histologic findings demonstrated that calcium deposition was the cause of cuff rupture. To our knowledge, based on a review of the English literature, this is the first case report in which the progression from calcifying tendinitis to rotator cuff tear has been serially observed.