The present invention is related to an open-end wrench including a first jaw and a second jaw and a throat section connected between rear ends of the two jaws. A toothed section is disposed on the inner side of the first jaw. The toothed section has multiple sharp teeth and a wide tooth positioned behind the sharp teeth. The wide tooth has a largest width among all the teeth. The bottommost point of the throat section is spaced from a front end of the first jaw by a first length. The bottommost point of the throat section is spaced from the tooth crest of the wide tooth by a second length, which ranges from ⅓ to ½ the first length. The toothed section has a length, which is about ⅖ the first length. The width of the wide tooth is 0.325 to 0.375 the length of the toothed section.