Intrapericardial extralobar pulmonary sequestration in a neonate. A huge pericardial effusion was diagnosed during fetal ultrasound examination performed in the 42nd week of pregnancy on a healthy 25-year-old woman. Immediately after the birth, a two-dimensional echocardiogram confirmed this finding in the infant, and an intrapericardial kidney-shaped solid mass measuring 45 x 56 x 15 mm, completely surrounded by pericardial effusion, was visualized to the left part of the heart. The heart was normal. No signs of cardiac tamponade were seen. At the age of two days, the mass was surgically resected and the pericardial fluid evacuated. Microscopic examination revealed that the mass was formed totally of normal lung tissue surrounded by normal pleura. To the best of our knowledge, this is the first case of intrapericardial extralobar sequestration consisting of an accessory lung with completely normal lung tissue. 