OBJECTIVE: To search for the operation timing and methods for obstetrical brachial plexus injury (OBPI). METHODS: Thirty-two children with upper OBPI were treated by microsurgical procedure from October 1997 to April 2001. The average age of patients was 10 months, ranged from 3 months to 24 months; of them, 19 were below 6 months while 13 were over 6 months. Surgical procedure included neurolysis(n = 12), coaptation after resection of the neuroma without function (n = 7), phrenic nerve transfer to anterior cord of upper trunk or musculocutaneous nerve (n = 7) and intercostal nerves transfer to musculocutaneous nerve(n = 6). The children underwent operation with microsurgical technique and 7/0 or 9/0 nylon was used for nerve suture. RESULTS: Thirty cases were followed up for 21 months postoperatively; the excellent and good rate was 76.7% (23/30). The results of the children under 6 months were better than those over 6 months. CONCLUSION: The microsurgical operation might be considered at the age of 3-6 month infants who had shown little or no improvement in elbow flexion. Neurolysis and nerve coaptation are superior to neurotization. The appropriate procedure should be selected according to the findings of exploration.