Illnesses commonly encountered in the ICU, such as sepsis, have frequently been associated with neuromuscular weakness and may play a role in the development of CIM and CIP, whose incidence in the critically ill is greater than initially reported. Although difficult to diagnose from history and clinical/laboratory findings alone, the use of electromyographic and nerve conduction testing is helpful in establishing these diagnoses. Information regarding prognosis of these disorders is limited, and there are no specific therapies that improve outcome. Acquired neuromuscular weakness in the ICU affects a significant number of patients and may continue to affect their quality of life long after discharge. Although diagnostic techniques are readily available, additional research is necessary to obtain adequate prognostic information and therapeutic options for these patients.