Computed tomography of the soft tissues of the shoulder in cases of calcifying tendinitis of the rotator cuff provides the following information: 1. Localisation of the calcium deposits within the rotator cuff. 2. Contours and density of the calcium deposits correlated with the clinical findings as described by Uhthoff et al. Ill-defined contours and non-homogeneous deposits are associated with more severe clinical features. 3. Computed tomography shows that apatite particles, which are not visible radiologically, may penetrate into the shoulder joint and produce synovitis with an effusion. This is of importance in local therapy.