Neuromuscular weakness in critically ill has been increasingly reported in the recent years. Occasionally it may lead to difficulty in weaning the patients from mechanical ventilation, which is difficult to diagnose clinically. Though in well-planned studies the incidence has been reported to be high, the diagnosis is often missed due to the presence of various confounding factors in the form of drug effects, underlying disorder and coexisting abnormalities of the central nervous system. A high index of suspicion with detailed neurological and electrophysiological examination is required for an early and accurate diagnosis. A wide spectrum of disorders and drugs can be responsible for the critical illness neuromuscular abnormality. The most frequent and defined disorders include; critical illness polyneuropathy (CIP) which is characterized by a sensorimotor reversible polyneuropathy presenting as distal symmetrical weakness with loss of deep tendon reflexes. Acute myopathy is another important disorder in this group which usually presents with quadriplegia often related to steroid use. Persistent blockade of neuromuscular junction is also defined in critically ill patients. It is, therefore, important to understand these disorders and their implications in the management of these patients. Some of the conditions require prolonged neuro-rehabilitation. The various acquired disorders leading to neuromuscular abnormalities in critical care, and their diagnosis and management are discussed.