Villous contraction frequency, lymph flow, blood flow, and arteriovenous oxygen difference were measured in dog jejunum. Venous pressure elevation and plasma dilution were used to increase capillary fluid filtration. Both perturbations produced concomitant increases in villous contraction frequency and lymph flow. A highly significant correlation (r = 0.83, p less than 0.001) was obtained between villous contraction frequency and lymph flow. This finding, coupled with the observation that stimulation of net fluid absorption increases villous contraction frequency, suggests that villous motility is increased by a myogenic response elicited by increments in interstitial fluid pressure. In another series of experiments local arterial pressure was reduced in 20-mmHg steps from 120 to 20 mmHg. Although blood flow fell proportionately to arterial pressure, villous contraction frequency and oxygen uptake were maintained at a normal level when arterial pressure was between 120 and 60 mmHg. Villous motility and oxygen consumption fell progressively as arterial pressure was reduced below 60 mmHg. This observation indicates that ischemia does not alter villous contraction frequency unless blood flow is reduced below the level necessary to maintain normal tissue oxygenation.