Abstract In experiments with the square wave electromagnetic flowmeter, portal vein flow in 20 normal dogs averaged 21.4 c.c. per kilogram per minute, and hepatic artery flow averaged 11.3 c.c. per kilogram per minute, giving a total blood inflow to the liver of 32.7 c.c. per kilogram per minute. Splenectomy and gastroesophageal decongestion resulted in a reduction in PVF of 23.3 percent and a decrease in PP of 24.3 percent. This reduction persisted in 2 dogs in which measurements were made 2 years after operation. The HAF after this operation increased in 55 percent, remained the same in 35 percent, and decreased in 10 percent of the dogs. Portal vein occlusion for 15 to 20 minutes led to profound shock, partly a consequence of splanchnic pooling and, possibly, partly a consequence of anoxic effects in the liver or intestine. The decrease in PVF or HAF did not seem to have a constant definite effect on the flow in the other vessel in the present study. It seemed, however, that HAF tended to increase in the majority of cases when the PVF was diminished.