Abstract: A diffuser drape for use in surgical procedures includes a sheet with an elliptical aperture therein for placing over the patient with the aperture defining the area of the proposed surgical incision; an annular, elliptical air duct on and attached to the sheet surrounding the aperture, the air duct including a diffuser ring on its lower, inner side surrounding the aperture when in use for diffusing clean air radially outwardly into the area above the aperture to keep the area of the incision clean, the ring having a non-uniform elliptical configuration, i.e. the ends of the diffuser ring are narrower than the sides thereof; and an air inlet integral with the air duct at each end thereof for introducing clean air into the duct for passage through the diffuser ring and the remainder of the duct.