Graft hyperperfusion in small-for-size grafts (SFSG) is considered the main causal factor of small-for-size syndrome (SFSS). We compared SFSG with a graft-to-recipient body ratio < or =0.8, with and without graft inflow modulation (GIM) by means of a hemi-portocaval shunt (HPCS). Thirteen patients underwent adult-to-adult living donor liver transplantation (AALDLT): G1, n = 5 [4 right livers (RL) and 1 left liver (LL)] without GIM, and G2, n = 8 (4 RL and 4 LL) with GIM. In G2 patients, portal vein flow (PVF) was significantly reduced by HPCS: 190 +/- 70 mL/min/100 g liver in G2 vs. 401 +/- 225 ml/min in G1 (p = 0.002). One- and 6-month post-transplantation graft volume/standard liver volume (GV/SLV) ratio was of 72% and 79.5% in G1; 80% and 101% in G2 (p = ns). SFSS was observed in three G1 recipients (who were retransplanted), but in none of the G2 patients. At 1-year, patient and graft survival was respectively of 40% and 20% in G1, 87.5% and 75% in G2 (p = 0.024 and 0.03). It is concluded that drastic reduction of PVF by means of HPCS improves overall patient and graft survival by averting the occurrence of SFSS. Graft inflow modulation through HPCS reduces the risk of complications when transplanting SFSG in adult recipients.