The critical illness polyneuropathy has an acute onset and an axonal predominantly motor nature. It occurs in sepsis or in multiple organ failure usually requiring mechanical ventilation in critical care units. Electroneuromyography corroborates the diagnosis. Usually it courses satisfactorily. We report on a 35-year-old female patient who, after a permanence in a critical care unit due to sepsis and removal of a dead phetus, developed tetraparesis. She had an important improvement in four months. Electromyography showed reduction of amplitude of motor and sensory action potentials, positive waves and fibrillations. The sural nerve biopsy showed axonmyelinic neuropathy. These findings are consistent with those in literature and we believe they support the diagnosis of critical illness neuropathy.