Venous pressure in the normal animal tends to be stabilized by 2 mechanisms, variations in the peripheral vascular bed and the variable response of the heart to the venous load. Under conditions of body rest the venous pressure shows little variation. The influence of respiration, gravity, sex, age, and muscular exercise is considered in some detail. Methods of measurement in man are given and discussed. Variations in venous pressure in various types of disease are considered, and it is concluded that a persistent abnormally high venous pressure occurs only in cardiac incompetence, irrespective of cause. Cardiac incompetence is denned as a state in which the initial load upon the heart, as represented by the venous pressure, exceeds the physiological limits of the heart muscle to respond with increased work.