A master oscillator power amplifier (MOPA) system in which the output from an end-pumped Nd:YAG oscillator cavity dumped at 500 kHz is scaled up by a four-stage Nd:YVO4 amplifier is reported. Decrease in extraction efficiency of the amplifier chain with crystals different from that in the oscillator was analyzed. With the 5.4 W seed output, 118 W of power was extracted from the amplifier chain at the pump power of 345 W, with an extraction efficiency of 34.2% and an overall optical–optical efficiency of 30.9% for the MOPA system. The beam quality factors were measured as M x 2 =1.45 and M y 2 =1.59 in two orthogonal directions, respectively.