The Morgagni hernia is a rare condition caused by the disturbances in the embryonal development of the diaphragm. The high pressure in the abdominal cavity during the persistent constipations or in pregnant women seems to be important predisposing factor apart from advanced age, obesity, vertebral column deformities and the connective tissue diseases. That is why the Morgagni hernia is very rarely diagnosed in children but usually in women in their fifties. We present the case report of our patent who was admitted to the Department of Internal Diseases for the diagnostics of lasting for 3-4 months weakness, chest pains and the episodes of palpitations. During her stay in our Department the routine chest X-ray examination was performed, that showed the unexpected result. The diagnosis of Morgagni hernia was afterwards confirmed in the computed tomography. Even though the risk of the acute abdominal conditions in the dislocated parts of gastro-intestinal tract our patient did not agree to proposed operation.