The postoperative left ventricular function (LV) of Jatene's operation for transposition of the great arteries (TGA) was evaluated by angiocardiography and echocardiography in 39 patients. In 16 patients repaired at less than 3 months of age, left ventricular endodiastolic volume (LVEDV) was significantly decreased at the angiography 2 months after repair: form 215 +/- 685% normal of preoperative LVEDV to 120 +/- 14% normal postoperatively (p less than 0.05) in 7 patients with simple TGA (Group IA), and from 220 +/- 64% normal to 130 +/- 33% normal (p less than 0.05) in 8 patients associated with ventricular septal defect (Group IIA). On the other hand, among 24 patients repaired at 3 or more months of age, 19 patients with simple TGA (Group IB) showed the significant increase of LVEDV (from 159 +/- 40% normal to 183 +/- 23% normal, p less than 0.05), and 5 patients associated with ventricular septal defect (Group IIB) showed no remarkable change (from 208 +/- 96% normal to 193 +/- 23% normal). There was no significant difference of postoperative pulmonary artery (PA) wedge pressure among the four groups. Postoperative left ventricular diastolic dimension (LVDd) revealed the tendency of normalization in all groups during the first postoperative year. Group IA and IIA completed the normalization of LVDd in 2 months and Group IIB in 6 months after the repair. However, LVDd in Group IB could not decrease to normal range even in 12 months after repair. There was a significant correlation between postoperative LVDd and the age at PA banding in 14 patients of Group IB, who had the preparatory PA banding for LV training.(ABSTRACT TRUNCATED AT 250 WORDS)