The relation between pulmonary vascular pathology and hemodynamics in 81 patients with congenital heart disease complicated by pulmonary hypertension was studied. Slight to marked increase of mean pulmonary pressure (MPAP) was seen in 5 of them, but no vascular lesion was found. 59 of the 81 cases had marked increase of MPAP and Grade 1-2 pulmonary vascular lesions, and cyanosis was seen clinically. Postoperative effects were satisfactory, indicating that not all patients with cyanosis contraindicated surgical treatment. The rest (17) of the 81 patients had most marked increase of MPAP and Grade 3-4 pulmonary vascular lesions with good postoperative results, but long-term results await follow-up observations. It is thought that Grade 4 pulmonary vascular lesion should be considered as a contraindication for corrective surgery.