In the introduction the authors describe the anatomical features of the subacromial space from which the concept of impingement syndrome is derived. In a review of the literature they describe the development of views on the pathology of the subacromial space. According to Neer (11) impingement syndrome develops i three stages. In the subsequent part of the paper the authors describe structural and functional changes which have an impact on the course of the impingement syndrome. They emphasize detailed assessment of the patient's subjective complaints and describe the comprehensive clinical examination as well as X-ray imaging methods. The subsequent part is devoted to conservative and surgical treatment with special attention to arthroscopic and open subacromial decompression. The final part of the paper deals with the problem of after-treatment. Key words: impingement syndrome, anatomical definition, diagnosis and treatment of subacromial decompression after-treatment.