Portal circulation in patients with chronic liver disease was evaluated by per-rectal portal scintigraphy, and per-rectal portal shunt indices were calculated to estimate the extent of the portosystemic shunt. The purpose was to identify patients with cirrhosis at special risk of developing esophageal varices. The cumulative incidence of varices in 3 years of the study in patients whose shunt index was originally 20% or over, was significantly higher than that in patients whose shunt index was originally under 20%. The cumulative survival rate in 7 years of the study in patients whose shunt index was originally under 70% was significantly higher than that in patients whose shunt index was originally 70% or over. The information obtained by calculating the shunt index could be used by physicians in out-patient clinics when deciding the schedule with which to monitor patients using barium esophagogram or endoscopy, and choosing the examination method.