The relationships between the Marangoni effect and conditions of heat pipes, such as dimensions, heat transfer rate, initial concentration of working liquid and temperature of the cooling water, were investigated by considering the heat and mass transfer in two-component heat pipes. It was found that temperature and concentration gradient on the liquid-vapor interface becomes larger near the entrance of the cooling section, where the boundary layers of temperature and concentration were not fully developed. It was also found that in utilizing the Marangoni effect for flowback of the working liquid, it is preferable that the Marangoni number increases in the section in which the quantity of liquid for flowback increases. It was also shown that the condensate thickness does not necessarily became larger from the cooling edge to the entrance and is usually less than 0.3 mm for typical heat pipes, which is acceptable for wickless heat pipes. These results can not be explained by a simple model in which the effect of mass diffusion in the vapor phase is neglected.