At a meeting of the Chicago Orthopedic Club the winter of 1935 at which Dr. H. Winnett Orr spoke on his treatment of osteomyelitis, there was considerable discussion pro and con as to its value. Several different views were expressed. Some claimed unequaled good results with this method, others unrivaled poor results, stating that it was no better than other ways. As a consequence no definite conclusion could be reached. It was determined, therefore, to review the record of cases of osteomyelitis treated by Orr's method in the orthopedic service at Cook County Hospital with the hope of throwing more light on the subject. Hence this compilation. The orthopedic service of Cook County Hospital is divided among six physicians. Most of the cases of chronic osteomyelitis, together with some of the acute ones, are sent to the orthopedic service, but occasional cases are treated in the general surgical services, of