A literature review related to miniature and micro heat pipes is given. It is found that longitudinal groove designs are crucial to increase the heat transport capacity of miniature heat pipes. In addition to the operational limitations of conventional heat pipes, micro heat pipes may be subject to the vapor continuum limitation, which may prevent micro heat pipes from operating under lower working temperatures. An analysis of the capillary limit reveals that the disjoining pressure may play a role in heat transfer for the micro heat pipe and may increase its heat transfer capacity.