Reduction of the physiologic retroversion of the humeral head can lead to shoulder luxation. After shoulder luxation it can also lead to shoulder instability. The aim of the paper was to check the level of humeral head retroversion in patients with anterior shoulder instability and to estimate the effectiveness of treatment of this instability with the derotational Weber osteotomy. The study included 38 patients, 34 males and 4 females, ranged 16-48 yr. (mean 31) treated in our Clinic. Every patient was done CT in order to estimate the level of humeral head retroversion. Patients with reduced humeral head retroversion qualified for operational treatment with Weber method derotational osteotomy. The outcomes were estimated according to the Rowe and Zarins score. 34 patients had excellent or good results. Pain was retreated, patients could come back to their normal activities, before the first luxation. Only 4 patients had another luxation in spite of our treatment. The control CT showed that the humeral head retroversion was 30 or more degrees. The arthroscopy was performed, the Bankart lesion was found and the patients were qualified for treatment this lesion. Weber osteotomy could be the satisfactory method of treatment of anterior shoulder instability in patients with physiologic reduction of humeral head retroversion.