This paper presents the test results and data correlation for the Heat Pipe Performance Flight Experiment which was a Class D middeck experiment flown aboard the Space Shuttle Columbia (STS-52) in October of 1992. Three categories of heat pipe performance were examined: static mode, operation under applied acceleration, and re-wicking capability. Two aluminum/freon axially grooved heat pipes, ten copper/water axially grooved heat pipes, and four fibrous wick copper/water variable conductance heat pipes were tested. Ground and flight test results for the axially grooved heat pipes are discussed and correlated with analytical models. Correlation of flight test data for cryogenic axially grooved oxygen heat pipes and a description of the Groove Analysis Program (GAP) is also presented.