Of 29 patients with hernia Bochdaleck there were 11 in the non surgical group and 18 in the surgical group. 14 were operated in the first 24 hours of life, and 4 patients after that time. No patients in the non-surgical group survived. In patients who were operated upon in the first 24 hours of life, 5 survived, and after that time 3. In all cases the transthoracic approach was used. The investigation did not permit any safe judgement of the preoperative treatment. On these conditions multiple anomalies combined with prematurity and intrauterine asphyxia had some influence on, whether a patient lived so long, that an operation could take place. Gastro-intestinal anomalies had a certain prognostic significance in the postoperative period. In cured patients the severity of a complicating cardiac failure could be of some importance.