Transient neuromuscular impairment resulting from prolonged inhalation of halothane and enflurane. Inhalation anesthesia first with halothane followed by enflurane relieved a patient with status asthmaticus who was refractory to conventional therapy including mechanical ventilation. After 13 days of anesthesia while on mechanical ventilation and employing nondepolarizing muscle relaxants, significant neuromuscular impairment, manifested by tetraplegia and sensory disturbance, developed. Anesthesia was discontinued on day 14, and the patient was weaned from mechanical ventilation on day 16. Over the next two months, the neuromuscular impairment markedly improved. Halothane was associated with cardiac arrhythmias and hepatitis necessitating replacement by enflurane. Enflurane appeared to be as effective a treatment for refractory asthma as halothane. The most probable cause of the neuromuscular impairment in our patient was the long-term use of inhalation anesthetics or nondepolarizing muscle relaxants. 