Myasthenia gravis is one of the diseases of which no cause is known until now. It manifests various symptoms according to the involved muscle group and it is caused by the presence of circulating antibodies to acetylcholine receptor, resulting in disorder in the neuromuscular junction. Among the muscle groups in the human body, it affects ocular muscle selectively and also the other cranial muscles. It also is characterized by fluctuation of the symptoms and ameloration of the symptoms by the administration of cholinergic drugs. It can be diagnosed by single muscle fiber electromyography but the most significant finding is demonstration of circulating antibodies to acetylcholine receptors. In the office it is easily suspected through history and physical examination including diagnostic trial of administration of cholinergic drugs like edrphonium and neostigmine. Recently the authors experienced 5 cases of myasthenia focal to larynx and soft palate which improved markedly with the administration of cholinergic drug after certifying no organic lesion in the respective organs.

Case I : The patient is a 42-year-old male who has suffered from hoarseness of 4 months' duration. There was no specific abnormality found through history and physical examination except incomplete approximation of both vocal cords. He received 0.5mg of neostigmine and showed loss of hoarseness and on indirect examination nearly normal approximation of both vocal cords was observed about 20 minutes after injection intramuscularly.

Case II : The patient is a 26-year-old female who has suffered from hoarseness for about 10 days. According to the patient the hoarseness is more prominent after much talk. On indirect laryngoscopic exam small chink was found in the posterior part of the glottis during phonation. She received 0.5mg of neostigmine as a diagnostic trial and hoarseness disappeared about 20 minutes after intramuscular injection.

Case III : The patient is a 16-year-old male who presented with hoarseness of about 2 years duration. There was no specific abnormal finding on the indirect laryngoscopy except incomplete approximation and slight bowing of both vocal cords. The patient received 0.5mg of neostigmine resulting in satisfactory improvement of hoarseness.

Case IV : The patient is a 25-year-old female who complained of hoarseness for about 10 days. The patient showed incomplete approximation of both vocal cords. This patient received 0.5mg of neostigmine intramuscularly and marked improvement of hoarseness was noted about 20 minutes after injection.

Case V : The patient is a 27 year old female who was consulted from the N-S department of our hospital. Because of dysarthria, dysphagia and nasal voice. At the second examination at our department. She was suspected as myasthenia of the soft palate with normal vocal cords. She received 0.5mg of neostigmine intramuscularly and improvement of the symptoms was noted about 10 minutes after injection. Myasthenia of larynx or soft palate is one of the symptoms of myasthenia gravis caused by affection of neuromuscular junction of motor nerve of the larnx or soft palate. It is very important to diagnose this disorder early for the benefit the patient can get through therapy but the more important thing is recognition and early management of the crisis of this disorder. In diagnosing this disorder the administration of cholinergic drug is simple and convenient. It can be done with great safety when atropine is administered prior to cholinergic drug.