Conventional methods for vascular access and bile collection in the rat, such as the isolated perfused liver, study under anesthesia, and animal restraint, do not allow study of a physiologically intact rat. A simple technique for vascular access and monitoring of biliary secretions in the intact, unrestrained, unanesthetized rat for extended periods of time is described. Sample experiments demonstrated a 20% complication rate and an 85% 24-hour survival. This model may prove useful in studies requiring chronic vascular and visceral catheterization in the awake rat.