During the period from January 1980 to September 1988, 59 patients suffering from brachial plexus injury, have admitted to Seoul National University Hospital. Fifty-four patients were male and 5 patients were female, and age ranged from 6 to 58 years (mean:26.8 years). The most common cause of injury was traffic accident accounting for 66% (39patient), and among them 24 patients(62%) had the motor cycle accident. Birth injury, stab or gun shot wound, fall down and industrial hazard were following causes. Fracture and dislocation of involved limb accompanied in 19 patients(32%) and 2 patients of arterial injury were also found. EMG and cervicsl myelography with or without CT were performed in almost all the patients and MRI was performed in selected patients. Forty-five patients(76%) had supra-clavicular lesion and 14 patients (24%) had infra-clavicular lesion. In supra-clavicular lesion, upper roots or whole roots were involved in most of cases. Forty-nine cases were treated with conservative treatment for more than 8 months and operative procedures were performed in 36 cases. In operative cases, 30 patients were followed up for more than 1 year (average 24.3 months). Signs of root avulsion were found in 25 out of 31 cases of cervical myelography. MRI was performed in 7 cases, but it was inconclusive in diagnosis of root involvement. Infra-clavicular lesion showed better prognosis than supra-clavicular lesion. In supra-clavicular lesion, upper root involvement had the best prognosis. A pseudocyst detected by myelography usually precluded recovery in the root at the level of pseudocyst. Result of reparative treatment was better than that of conservative treatment. Overall satisfactory result in reparative treatment was 36%. However, if we include neurological improvement, positive result was 53%. Complete recovery was gained in half cases of neurolysis and other half showed no recovery, but all the cases of neurotization showed poor result. Reconstructive surgery including arthrodesis or muscle transfer can be effective treatment method, if it is performed properly on a selective patient.