There are several operations in the production of petroleum in which three-phase concurrent flow of fluids takes place. In some cases this type of flow necessarily must occur, such as the lifting and transportation of gas, crude oil, or condensate and water from the reservoir to the first separator in the field. In another operation, three-phase flow is encountered when glycol is injected into a pipeline at the well-head with oil and wet gas, in order to prevent freeze ups from gas-hydrate formation. The design of piping for vertical, horizontal, and inclined multiphase flow has been done largely by the expensive route of trial and error. Poettman, et al., have analyzed data on a number of wells flowing oil, gas, and water vertically. This laboratory study was undertaken in view of the current interest in the concurrent flow of oil and gas in field-gathering pipelines along with the injection of a third water phase such as glycol.