We report highly efficient laser operation of praseodymium-doped LiYF4 in the green spectral range. The influence of the crystal length and pump light focusing on the laser performance has been studied. The pump radiation was delivered by InGaN laser diodes. Optimizing the setup for a 2.9mm long crys tal with a doping concentration of 0.5% led to an electric to green laser power conversion efficiency as high as 7.4%. With 500 and 1000mW of pump light power, output powers of 179 and 358mW have been reached, respectively. With respect to absorbed power, slope efficiencies of up to ∼60% have been achieved.