The author tries to demonstrate that the term "periartritis" created by Duplay is improper, since this disease is generally part of several different lesions only. After brief considerations on anatomo-physiology of the shoulder, the author summarizes the lesions of shoulder as follows: 1) tendinitis of supraspinatus and sub-deltoid bursitis; 2) rupture of supra-spinatus tendon; 3) lesions of the long tendon of biceps; 4) formation of periarticular adhérences, "frozen shoulder". He studies each group in its pathogenic, clinical and therapeutic point of view emphasizing the importance of procaine injection, anesthetic test, and surgical exploration by the transacromial via and the physiotherapy carefully supervised by the orthopedist.