Fifteen additional patients with Milwaukee shoulder syndrome are described, bringing our total series to 30 cases. The condition occurred predominantly in elderly women and was characterized by severe glenohumeral joint degeneration and dissolution of the fibrous rotator cuff. Synovial fluids contained few leukocytes, but were often blood tinged. Basic calcium phosphate crystal aggregates and particulate collagens were noted in nearly all fluids, and collagenase activity was detectable in some, but not all, fluids. The knee joints were involved with a similar process in about half of our patients. In contrast to primary osteoarthritis, lateral tibiofemoral compartment involvement was common. Factors that may predispose to this syndrome included deposition of calcium pyrophosphate dihydrate crystals, direct trauma or chronic joint overuse, chronic renal failure, and denervation.