Acute infectious processes of all types stand out as potentially lethal complications in the aged and in the chronically ill, and acute septic arthritis is not a rare form of infection in the older age groups—especially in those persons who have underlying chronic disorders. Since the host-response to infections in this group is notoriously atypical, the recognition of septic joint disease depends primarily upon the diligence with which it is sought. Ten cases of acute septic arthritis have been seen in an 18-month period at King County and Seattle Veterans Administration Hospitals, a case load casting doubt on the notion that acute septic joint disease was to become a medical curiosity.1 A retrospective study of three and one-half years' experience in the same hospitals yielded nine additional patients in whom pyarthrosis had been established. Thus, a total of 19 cases was seen over a period of five years. The