A ring applicator device and method for applying an elastic occluding ring to an anatomical tubular structure which comprises an inner cylinder slidably disposed within an outer cylinder, forceps means slidably disposed within said inner cylinder, and means for moving said forceps means into and out of the inner cylinder and for ejecting an elastic ring from the end of said inner cylinder by displacing said outer and inner cylinders relative to each other. The ring applicator device and method is particularly effective in withdrawing a reproductive tubular member inside of the inner cylinder, thereby forming a loop therein, and displacing the inner cylinder relative to the outer cylinder to eject the elastic ring around said loop, in a one-step operation.