[Introduction] Tenascin-C (TN-C), an extracellular matrix glycoprotein, is not normally expressed in the liver but transiently reappears under various pathologic conditions to play important roles in tissue remodeling during inflammations such as chronic HCV hepatitis. Elevated serum TN-C levels in those patients were reported to reflect the tissue injury and remodeling. It is considered that serum TN-C could be effective as a marker of liver ischemia reperfusion injury and regeneration insufficiency in living donor liver transplantation (LDLT). In this study, TN-C was measured to clarify whether it could be used as a marker of liver regeneration insufficiency and prognosis in patients with LDLT. [Materials and Methods] The serum TN-C were analyzed in the 74 patients with LDLT between Jan. 2002 to Dec. 2005 at Mie University. TN-C on pre-op, post-op day 1, 7, 14 and 28 were measured. We analyzed various prognostic factors: age, sex, C-P, MELD, GRWR, warm ischemic time, cold ischemic time, blood loss, Plt, T-Bil and TN-C. ROC of TN-C was analyzed for 90- day death. Cox regression and Kaplan-Meier according to TN-C were analyzed for overall survival (OS). [Results] 9 patients died within post-op day 90. In the univariate analysis, C-P, MELD, Plt on day1, 14 and 28, T-Bil on day7, 14 and 28, TN-C on pre-, day7, 14 and 28 were prognostic factors. In the multivariate analyses used logistic regression, TN-C on day 14 (TNC14) was an only independent prognostic factor for 90- day death (p<0.05, odd’s ratio: 1.011). In analyzed ROC of TNC14, AUC was 0.814, sensitivity was 77.8% and specificity was 75.4%. With the optimum cutoff value of TNC14 was established at 190 ng/mL: 24 patients showed high TNC14 (≥190 ng/mL) and 50 patients showed low TNC14 (<190 ng/mL). GRWR was significantly lower in the high TNC14 group (median:0.973 vs 1.08, p<0.05).According to Cox regression for OS, TNC14 was a prognostic factor (median follow-up of month: 104, p<0.05,odd’s ratio: 1.004). Significant difference in OS between the low and high TNC14 groups (Log Rank: p<0.05) was noted. [Conclusions] Serum TNC14 can be used as the marker of prognosis in patients with LDLT. If graft size is smaller, serum TNC14 is potentially useful for early diagnosis of postoperative liver regeneration impairment.