We report the performance of a V-band 5-stage high power amplifier MMIC using a millimeter-wave 0.1 μm GaAs pHEMT. It has demonstrated that an output power of 28.8 dBm (759 mW) at 1 dB compression point with 17.8 dB power gain and 14.2% PAE at 59 GHz. And it delivers an output power of 28.9 dBm (776 mW) at a saturation point. These results represent, to the best of our knowledge, the highest output power and power gain for single-ended MMICs.