✓ The authors review the cases of 116 infants treated consecutively for birth-related brachial plexus injuries. Twenty-eight infants with upper brachial plexus lesions who showed no neurological improvement by 4 months of age were selected for early surgical reconstruction (at a mean age of 5 months). Neurological improvement of the affected arm was observed in more than 90% (p < 0.05) of the children examined longer than 9 months after brachial plexus reconstruction. A conservatively managed control subgroup of 44 children, first examined at less than 3 months of age, demonstrated neurological improvement by 4 months of age and continued to show improvement at 1 year of age. Early surgical reconstruction is recommended for infants with birth-related upper brachial plexus injury who show no neurological improvement by the age of 4 months.