The technique of biopsy occupies a position of undisputed importance as a diagnostic procedure. It has not found wide application in the field of rheumatic diseases, however, because of the expense and period of incapacity involved with conventional arthrotomy. The situation was significantly improved, we believe, in 1951, when Polley and Bickel1 described their experiences with an instrument for punch biopsy of the synovial membrane. In several subsequent reports2-4 these authors have confirmed their opinion regarding the diagnostic value of the method. Our initial report 5 was in agreement, stating that the procedure was considered a practical diagnostic method. The Polley-Bickel instrument (Fig. 1) is simply constructed. The main part is a hollow stainless-steel tube with a trocar point and a hooked opening on the dorsal surface near the trocar tip. A hollow tubular knife with a sharp cutting rim fits inside the outer tube and is used