Since the first description of Bolton et al., critical illness polyneuropathy (CIP) and critical illness myopathy (CIM) are increasingly observed as a complication in intensive care patients. CIP and CIM commonly occur in patients with an ICU length of stay exceeding one week. Typically, these patients show weakness of the limbs and difficulties in weaning from the respirator. Neurological and electrophysiological examinations as well as muscle biopsies if myopathy is of concern may help to characterize and identify polyneuropathy and myopathy.