1. A case of recurrent posterior subluxation of the shoulder is described. After failure of a soft-tissue repair, a posterior bone block operation was performed.

2. The distinction between traumatic dislocations with tearing of the capsule or of the glenoid labrum, and habitual luxations from laxity of the capsule, is emphasised. Although the anterior rim of the glenoid was detached in this case, it is considered to fall into the latter category.

3. A posterior bone block provides a simple and efficient form of repair in this type of case. It is free from the disadvantage of causing limitation of rotation at the shoulder joint; it employs a principle which might well merit more application than at present in the repair of anterior dislocations.