In a prospective controlled study 167 patients with 167 primary traumatic anterior shoulder dislocations underwent early ultrasonograpic evaluation for rotator cuff tears. We found 53 (31.7%) full-thickness cuff tears in this group. Compared with a group of 93 healthy volunteers, we found with statistical significance more cuff tears in the patients aged < 60 years. Women ruptured the cuff more often than men. If the patient is not able to elevate the affected arm more than 90 degrees in the scapular plane 2 weeks after the dislocation, there should be a high suspicion of rotator cuff tear (76.7%). For early detection of relevant rotator cuff lesions, we recommend shoulder ultrasonographic examination and measurement of active elevation after each traumatic shoulder dislocation in the above mentioned age group.