1. A recently described disease consisting of articular-cartilage calcification with polyarthritis is discussed.
2. The literature is reviewed and four new cases are presented.
3. The roentgenographic picture is characteristic, consisting of calcification in the intermediate zone of articular cartilage.
4. The diagnosis is established by identifying crystals of calcium pyrophosphate in aspirated joint fluid by x-ray diffraction.
5. A theory of pathogenesis of the arthritis is presented.