Forty-one living donor liver transplantations (LDLT), including 11 pediatric and 30 adult recipients, were performed in Okayama University Hospital. Thirty-seven patients survive (overall survival rate 90.2%). Postoperative infection and rejection were analyzed. The incidence of bacterial and cytomegalovirus infection was 26.8% and 22%, respectively, but no patient developed lethal infection. Posttransplant lymphoproliferative disease occurred in 3 recipients who received additional pre- or postoperative intensive immunosuppressive therapy. Even though all recipients were administered a tacrolimus-based double or triple regimen including prophylactic programmed pulse therapy (methylpredonisone 10 mg/kg, days 5 to 7), 30 rejection episodes were observed in 19 patients(46.3%). Two recipients died of both steroid- and OKT-3-resistant rejection. Routine daily Doppler ultrasonography (US) revealed the presence of early severe rejection with hepatic hemodynamic changes in 7 patients. Patients exhibiting rejection with hemodynamic changes had a significantly shorter incubation period (8.8 +/- 2.2 vs 38.7 +/- 29.6 days, p < 0.01), more severe histological features(rejection activity index, 6.1 +/- 1.2 vs 3.0 +/- 0.5, p < 0.001), and higher peak alanine aminotransferase value (883 +/- 354 IU/L vs 198 +/- 115 IU/L, p < 0.01) than in those exhibiting rejection without hemodynamic changes. Diagnostic programmed pulse therapy plus frequent routine Doppler US may be useful in the diagnosis of and therapy for earlier and more severe acute rejection in LDLT.