Preheat grill. Cut medium potatoes into 6 equal pieces, or cut red potatoes in half. Cut each zucchini into 6 slices. Cut sausage into 12 slices.
Place 3 pieces potato, zucchini and sausage on each skewer, alternating them. Place skewers in shallow baking dish and pour Italian dressing over them. Marinate for 5 minutes.
Place skewers on grill and cook 5 minutes on each side or until potatoes are done. Use oven mitts to remove skewers from grill.