34 subjects with 36 obstetrical paralysis of the brachial plexus were studied. The diagnosis was made immediately after birth in the great majority. 5 pareses of the lower plexus, however, were only recognized later. All subjects were first seen by us under the age of 13 years, 25 during the first year of life. At follow-up the age of the 34 subjects varied between 3 and 24 years. 32 patients had undergone daily physiotherapy, in 5 electrotherapy had also been applied. There was no correlation between these treatments and the outcome. Of the 20 cases of paresis of the lower plexus 3 were severely handicapped after the age of 3. This was the case for 9 of the 12 patients with total paresis. Everyday activities of these patients are influenced by the motor deficit. Even subjects with relatively serious sequelae apparently enjoy an almost normal life and have a good self-image. A significant improvement generally occurred as early as the first 3 years of life.