An experimental study used pulsed ultrasonic Doppler techniques to determine fluid velocities in two-phase oil-water vertical pipe flow.1 The data acquisition system was based on a medical ultrasound instrument, modified as needed, and a microcomputer. Measurements were made in a pipe with an inside diameter of 7.25 in. [18.4 cm], part of the Multiphase Flow Loop in the Department of Petroleum Engineering at The University of Texas at Austin. This pipe is 42 ft [12.8 m] long and can be inclined at any angle. The ultrasonic measurements gave reasonable qualitative results in all regimes of which the flow facility is capable: the Doppler frequency was generally proportional to the phase velocities. More theoretical and experimental work is needed, though, to improve the quantitative accuracy and to increase the measurement range: measured velocities were generally too low, and the range limit is estimated to be approximately 6 to 12 cm into the flow, depending on the regime. Backflow is measured on the low side when the pipe is inclined from the vertical.