Ten years have elapsed since Bradley1first reported measurement of estimated hepatic blood flow (EHBF) using the sulfobromophthalein sodium (Bromsulphalein, BSP) method. In the intervening decade the basic principles upon which the technique is dependent have been the subject of numerous appraisals. Many have been critical of the accuracy obtained,* whereas others have substantiated the reliability of the method.† In spite of the controversy, its use in the study of the hemodynamics of the liver under various experimental conditions and in disease has gained impetus. The measurement of EHBF in cirrhotics ‡ following experimental hemorrhage,§ after arterialization of the liver,15during anesthesia16and drug administration, ∥ and subsequent to portacaval shunt ¶ are but a few of the situations where it has been utilized. Prior to introduction of the sulfobromophthalein sodium method, techniques for measurement of hepatic blood flow were cumbersome and impractical for use in the