The cause of paresis of the diaphragm after cardiosurgery is damage of the phrenic nerve. The diagnosis of paresis is based on X-ray examination, sonography and electromyography of the diaphragm. Plication of the diaphragm is indicated only in those children with paresis of the diaphragm who develop during spontaneous ventilation severe respiratory insufficiency. In the Cardiocentre of the Faculty Hospital Prague-Motol between 1983 and 1996 of 5333 children operated on account of heart disease 29 children were subjected to plication of the diaphragm, incl. five where the operation was made during the neonatal stage (17%), 20 in infant age (69%) and four were older than one year (14%). By the third day after plication 9 children (38%) could be disconnected from the respirator, by the 5th day 20 children (70%) by the 7th day 22 children (75%). In neonates and infants with postoperative paresis of the diaphragm, where spontaneous ventilation cannot be induced, plication of the diaphragm is according to the authors the method of choice. It is a rapid and safe surgical operation which reduces the period of artificial ventilation and its complications.