Forty-four children with obstetric brachial plexus palsy were assessed for both developmental attainment and behavioural problems. Analysis of the resulting data revealed developmental and behavioural problems previously not identified, particularly in those with more severe injuries. These effects were independent of the general condition of the child at birth, as indicated by their Apgar scores, Further studies are required to provide clarification of these children's difficulties, the mechanisms by which they occur and effective strategies to address them.