We inform about 20 patients (19 men, 1 woman) with acute acromioclavicular striking, type Tossy III, which were operated. By usual preoperative diagnostic and physical examination, x-ray standard pictures of the shoulder in two planes and x-ray panoramic picture (loaded with 10 kp and unloaded) in ap-axis we made an additional sonographic examination of the hurt shoulder. This is practiced in the commendable standardised pattern of DEGUM (German Society of Ultrasound in Medicine). After the standardised sonographic examination we focussed the acromioclavicular joint sonographically in a modified lateral vertical axis. All of the 20 examined shoulder joints belong to the stage Tossy III. In the preoperative diagnosis the difference in elevation between the lateral portion of the clavicula and the medial portion of the acromion amounts in comparison to the two shoulders (loaded versus unloaded shoulder joints) sonographically 6.2 +/- 2.6 mm (max. difference of the sides 10 mm), by the radiological examination 6.5 +/- 3.7 mm (max. difference of the sides 14 mm). The sonographical examination of the shoulder joint makes it possible to get more information about the acromioclavicular lesion, especially by an AC examination according to Tossy degree III. At present there is no possibility of substituting the standardised x-ray pictures in two axes to diagnose or exclude fractures.