In cases of myasthenia gravis, crisis can result either from increase in severity of the disease (myasthenic crisis) or from overtreatment with anticholinesterase drugs (cholinergic crisis). The patient is in imminent danger of death because of inability to breathe. Since 1958, the authors have observed 47 crises in 35 patients, and therapy has been re-evaluated. Emphasis has changed from use of more and more anticholinesterase drugs in treatment of crisis to the present concept of less and less drugs (with even complete withdrawal for approximately 72 hr), early performance of tracheostomy, and [ill]se of mechanically assisted respiration. The mortality rate in crisis has been reduced from 29 deaths in 67 crises, before 1958, to 8 deaths in 47 crises in the past 4 yr.