The determination of blood viscosity in man by a method based on Poiseuille’s

The viscosity of the blood is an important factor in any consideration of blood flow or peripheral resistance (1). In addition, a change in blood vis-cosity has been implicated in many clinical con-ditions (2-6). The determination of blood vis-cosity in man, however, has been limited by poor techniques of doubtful accuracy. With the meth-ods now available, blood is removed from the body and its viscosity determined relative to water. This relative viscosity is of limited value in any quantitative hemodynamic study, and cannot be converted into accurate absolute values because of changes occurring in the blood subsequent to its removal from the body. If the viscosity of blood in its unchanged state could be determined, a