Neuromuscular weakness in critically ill patients is a diagnostic challenge. Critical illness polyneuropathy, an important cause of failure to wean from assisted ventilation is often missed due to lack of suspicion and initiative to undertake regular bedside neurological and electrophysiological examinations in critically ill patients. We report two cases who developed motor weakness while receiving mechanical ventilation in whom axonal neuropathy was diagnosed on electrophysiological studies, establishing a diagnosis of critical illness polyneuropathy. Both patients had evidence of sepsis and multiorgan failure. One case could be successfully weaned off and weakness improved while other succumbed to the underlying illness.