A review of recent investigations on micro heat pipes of various geometrical designs, fabrication methods, operational environments and applications is presented, along with a comparative analysis of the performance of various designs, based on quantitative design parameters and performance indicators. A comprehensive report of the salient features of these investigations has been presented in a tabular form, in order to provide a quick reference of the state-of-the-art of micro heat pipe research. Both theoretical and experimental investigations have been included in this review, with special attention given to some of the new concepts and proposed designs for micro heat pipes, currently under development. Copyright (C) 2007 John Wiley & Sons, Ltd.