Neuromuscular weakness is a common problem in intensive care units. In patients with muscle weakness and difficulty in separation from the ventilator, especially hospital mortality and chronic disability are increased. Critical illness myopathy (CIM), critical illnesspolyneuropathy (CIP) and critical illness polyneuromyopathy (CIPNM) are the most common causes of muscle weakness and difficulty in separation from the ventilator in intensive care units. In this article, we report a patient who developed CIP in only 10 days of intensive care unitstay and discuss his rehabilitation period in the follow up as a case report. A 52-year-old male patient stayed in intensive care unit (ICU) andmechanical ventilation for 10 days because of tracheal fistulisation. During ICU stay, he had myoclonus which is not common in CIP, muscle weakness of four extremities especially in proximal muscles and hypoesthesia. Clinical symptoms and electrodiagnostic studies were compatible with critical illness polyneuropathy (CIP). There is no specific treatment for CIP; just supportive treatment and rehabilitation. Withrehabilitation programs, the patient was mobilized with a walker and bilateral ankle foot orthosis. During discharge, myoclonus decreased considerably. The initial and final functional independence measurement score and Barthel’s daily life activities index of the patient were 47/126and 0/100 versus 88/126 and 60/100. Rehabilitation has an important place in the early period and the diagnosis should be made as early aspossible and the patient should be included in the rehabilitation program early. Accompanying CIP with myoclonus is not common; but forour patient's myoclonus is a cause of muscle weakness and cerebral hypoxia. In the presence of myoclonus, CIP diagnosis should not be ruledout. Medical treatment and rehabilitation decreased myoclonus as well. Early rehabilitation increases the functional capacity of the patient,decreases the duration of ventilator use, and the patient leaves the intensive care unit early.