We prospectively evaluated the diagnostic value of sonography and magnetic resonance imaging (MRI) in 24 shoulders in 23 patients with suspected rotator cuff tears using arthrography as gold standard. Sonography demonstrated 14 of 15, MRI 10 of 15 rotator cuff tears, respectively. Sonography diagnosed seven of nine intact rotator cuffs correctly, MRI eight of nine. In a retrospective study we reviewed the diagnostic value of sonography and MRI in other pathologies of the shoulder including intra-articular pathology, humeral head and acromioclavicular joint pathology, and calcification. We conclude that with regard to cost and patient compliance, sonography should be the first radiologic examination in suspected rotator cuff tears if performed by an experienced sonographer. MRI is superior in depicting additional pathology and is less operator dependent. It may thus become the method of choice for the evaluation of the rotator cuff and related pathology in the future.