The operating principle of a rotating miniature heat pipe (RMHP) with a grooved inner wall surface is addressed. A mathematical model of the hydrodynamic performance of RMHPs is developed. A simple correlation for the friction coefficient of axial liquid flow including a vapor drag effect is proposed based on the numerical analysis of 2D laminar liquid flow in a groove. With the present model, the maximum performance and optimum liquid fill amount of RMHPs are predicted under various operating conditions. Influences of operating temperature, rotational speed and liquid-vapor interfacial shear stress on the maximum performance and optimum liquid fill amount are discussed. Pressure drops of the axial liquid flow and vapor flow are demonstrated.