We examined the difference between early cirrhotic patients with lower branched-chain amino acids (BCAA) to tyrosine ratio (BTR) (<4) and higher BTR (>4) in portal circulation using per-rectal portal scintigraphy with technetium-99m pertechnetate. Forty patients with Child-Pugh grade A cirrhosis and serum albumin level between 3.5 and 3.9 g/dl were enrolled in this study. Sixteen patients were infected with HBV and 24 with HCV. Thirteen patients had BTR<4.0 and 27 had BTR>4.0. Shunt index (SI) obtained through per-rectal portal scintigraphy was significantly correlated with BTR (r=-0.558, P<0.0002). ICGR-15 was most strongly correlated with BTR among six parameters representing liver reserve capacity. The mean SI of patients with BTR less than 4 (38.4+/-28.0%) was significantly higher than that of patients with BTR greater than 4 (17.3+/-14.3%) (P=0.0388). The mean concentration of serum BCAA did not significantly differ between the two groups, but the mean concentration of serum tyrosine in the patients with BTR<4 was significantly higher than that in the patients with BTR>4 (P=0.0081). These results suggested that the increase in porto-systemic shunt caused tyrosine passing through liver and stagnating in the serum, as a result of which BTR fall in early cirrhosis. In conclusion, decrease of blood flow through liver and increase in porto-systemic shunt might be partly responsible for deterioration of BTR in early cirrhosis.