There are many interactions between intestinal blood flow and absorption. These include the support of transcellular transport by O2 delivery; the passive effects of Starling forces on absorption, secretion, and mucosal conductance; the washout of absorbed materials; and countercurrent exchange. Blood flow hemodynamics, and absorption interact. Regulatory mechanisms add a tertiary influence to these interactions. Further progress in this area would be greatly helped by techniques that could measure blood flow and hemodynamic factors at the absorptive and secretory sites more precisely.