The safety and lack of undue operative stress on the donor are documented from an analysis of 100 parental donors, whose children (3 months to 17 years old), received LRLTx at our institution between June 1992 and May 1994. Survival rate of recipients was 86%. No primary nonfunctioning liver was observed. The donors were 56 mothers and 44 fathers. Their ages ranged from 19 to 51 years and their weight ranged from 44 to 80 kg. They received partial liver resections to harvest the grafts. With regard to the liver graft, the left lobe was used in 24 cases (group L) and the left lateral segment was used in 75 cases (group S). The right lobe was used in one case. In the two groups, blood losses were 242 +/- 5 (S) and 312 +/- 14 ml (L); operation times were 6.22 +/- 0.11 (S) and 7.15 +/- 0.21 hr (L), respectively; in both groups, the postoperative hospital stay was 11 days (S, L). No significant differences between the two groups were observed in peripheral RBC and WBC count or serum AST. An increase in total bilirubin was not observed. In the exceptional case using the right lobe, blood loss of 2300 ml necessitated a blood transfusion of 1000 ml, and the total bilirubin increased up to 4.0 mg/dl on the third postoperative day, which prolonged the postoperative hospital stay to 17 days. These results conclusively suggest that safety is guaranteed when the left lobe or the left lateral segment is used as the liver graft for LRLTx.