Trim ends off zucchini and then slice zucchini lengthwise into 1/4-inch-thick slices; place on a cookie sheet. Place oil and garlic in a small bowl or measuring cup; mix well. Brush oil mixture onto both sides of zucchini slices.
Remove zucchini slices from cookie sheet and place on the heated grill. Cook 2 to 3 minutes per side or until done. Serve immediately.