The semiology of the hand after brain damage is really rich. Its clinical evaluation remains quite difficult and must be integrated in the neuro-orthopedic and cognitive context. Deficiency, neuropsychological, analytic and functional status, must be assessed before any surgical decision aiming the improvement of prehension. Neuropsychological evaluation precise the hemispheric specialization: right hemisphere lesions conduct to unilateral spatial neglect while left hemispherical lesions determine language troubles and gesture impairment (apraxia). The analytical evaluation describes motor and sensitive function and assesses spasticity and pain. Concerning the functional assessment, the Enjalbert's score seems to be the most adapted to the upper limb. The assessment of hand deficiency and its origin is necessary to orientate the surgical decision and includes the Zancolli classification for the fingers and wrist and the House classification for the thumb. These classification used for cerebral palsy seems to be insufficient for all the different situations occurring after brain damage. A new classification is proposed based on 3 parameters: fingers extension, thumb abduction and supination. Surgical decision should be examined only after an adapted rehabilitation program.