Clinical examination of the tendon reflexes is helpful in localising lesions in the nervous system, which is an important step in the diagnosis of neurological disorders. The large intra- and interindividual variations of reflex amplitudes make interpretation difficult. Published interobserver agreement studies provide conflicting results. The diagnostic specificity of unequivocally abnormal reflexes is moderate to good (70-95%, decreasing with increasing age), but the sensitivity is lower (50-70%), both for peripheral and for central lesions. This implies that the finding of a clearly abnormal reflex pattern is often helpful, but the finding of normal reflexes usually does not exclude a neurological lesion.