Two surgical operations on patients with hemophilia are described. One was an appendectomy performed on a 26-year-old man with the laboratory findings and long history of hemorrhages characteristic of hemophilia. The other was a goniotomy in a 7-month-old boy with similar laboratory findings and a history of recent hemorrhages. In both patients the antihemophilic globulin (AHG) concentration was less than 1 % on assay. Infusions of fresh plasma were given before operation in both cases, and in the second case assays for AHG showed that adequate levels could be achieved by such infusions provided the apparatus was siliconized, the plasma chilled, and the infusion given rapidly. In the older patient the postoperative course was marked by some bleeding, but both patients recovered.