140 fractures of the olecranon were treated (69 conservatively, 71 surgically), of whom 71 were followed up (28 conservative, 43 operated fractures). The fractures are classified in 4 groups (A. transverse fractures, B. oblique fractures, C. comminuted fractures and D. fractures associated with other injuries in the elbow joint). Each of these groups is devided into 3 types according to the displacement of the fragments. Good results by conservative treatment were always seen in fractures with separation of the fragments less than 2 mm. A relative indication for surgical treatment is displacement from 2 up to 10 mm. Only surgical treatment can prevent non-union in fractures with separation of the fragments more than 10 mm. A new sheme for classification of the results is proposed, and late results of the followed up cases are reported. Immobilization of the elbow in full extension is rejected in the conservative treatment. The internal fixation of prestress type by the Weber technique and the osteosynthesis with Spongiosa-screw are the preponderant methods actually used in surgical treatment.