Authors reported about their experiences with newborn infants, who had transient myasthenia gravis; one disease developed in the fetal, others 10 in the early neonatal age. Direct correlation was found between the development of maternal polyhydramnios and the severity symptoms in newborns: risk of neonatal myasthenia gravis increased at these infants. Specific treatment included blood exchange transfusions and pyridostigmin (Mestinon) medication for 2-10 weeks. Five transient myasthenia gravis responded readily to blood exchange transfusions. Authors pointed out that in the early neonatal period the aetiology of an obscure respiratory inadequacy and hypoventilation might be regarded as transient myasthenia gravis.