In this paper, a method for measuring thermally induced lossesin high-power end-pumped solid-state lasers has been proposed. Using this method, we haveinvestigated the variation of thermally induced losses with pump power, for two differentNd3+-doped YVOsub>4/sub>crystals (0.5%, and 2%), and with the ratio of mode radius to pump radius (Wsub>1/sub>/Wsub>p/sub>)taking on the value of about 0.5 and 1, respectively. The results show that thermallyinduced losses increase with the rising of the pump power, and strongly depend on Wsub>1/sub>/Wsub>p/sub>;large mode sizes lead to significantly high thermal losses. The results also reveal thatthe Nd3+concentration of Nd:YVOsub>4/sub>crystal has important influence onthermally induced losses;in the situation of large mode sizes, the thermal lossesassociated with heavily-doped crystals are much higher than those of lightly-dopedcrystals, and the dependence on Wsub>1/sub>/Wsub>p/sub>is much stronger.