Thinking about the pumping and generated power of the longitudinally diode-pumped solid-state laser enhancement, the question of an active material cooling should be solved. One of the possible solutions is the active material cooling surface enlargement. Besides the cylindrical surface of the crystal, the laser rod front surfaces could be cooled through undoped ends. The temperature gradient effect in three various samples was investigated in a computer experiment, and the differences in generated output power were measured experimentally. The samples were three Nd:YAG rods - one conventional, one with one undoped end, and one with two undoped ends. The crystal samples were placed in sequence into a resonator 6 cm long and longitudinally diode-pumped. The dependencies of the generated power on the absorbed pump power have shown that with the two undoped ends the output power is more than twice as high as against the conventional Nd:YAG sample. The results were explained by a computer experiment based on the heat transfer equation solution where the changes of the temperature gradient were least for the Nd:YAG rod with two undoped ends.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.