GaN technology is revolutionizing the mm-wave spectrum, producing power amplifiers with power levels, bandwidths and efficiencies heretofore unachievable with any technology. In the last 5 years, this technology has produced an order of magnitude increase in the output power of MMIC amplifiers and by using power combining techniques, a 100 fold increase in power. Further, there have been substantial increases in bandwidth and efficiency. This talk will focus on these advances, reporting the latest state-of-the-art results at frequencies ranging from 30 to 120GHz. Examples include, at 30GHz, a MMIC producing a PAE of 40% with an associated output power of 10W, at W-band, a 2W MMIC with a bandwidth of 25GHz and at 116GHz an amplifier with 2–3W of output power.