Despite the great number of articles on chondromatosis of the joints which have appeared since Reichel's publication in 1900, the condition has remained an interesting problem which by no means is entirely solved. From a review of the literature one gets the impression that the diagnosis, which is very simple when the condition is outspoken, is made too often and that many conditions which belong to the group of hypertrophic arthritis are diagnosed as chondromatosis because of the presence of a great number of joint bodies. Chondromatosis of the joints is a rare condition. Only three cases were found in the extremely rich material of the orthopedic department of the State University of Iowa. A diagnosis of chondromatosis was made many times, but the diagnosis did not withstand a more critical analysis. Three cases are reported here which were interesting from a clinical and a pathologic point of view.