Abstract: A surgical device of the kind having a cannula fitted with a laterally extending wing or wings also includes a sheet of flexible material having an adhesive surface which is fixed to the wing or wings and is capable of folding forwardly beyond the wing or wings to engage the skin of the patient to hold both the cannula and the remainder of the device in position. This avoids the need for the separate piece of surgical plaster used in the past since the adhesive-covered flexible sheet is automatically to hand and is automatically located with considerable accuracy. With a double wing construction the flexible sheet is preferably fixed so as to extend from the rear edge of the wings and when folded forwardly this brings the layer of adhesive into contact with the upper surface of the wings and also into contact with the skin of the patient beyond the forward edge of the wings. The sheet of flexible material preferably carries a layer of pressure-sensitive adhesive covered by a removable barrier sheet.