Varactor diodes are now available with very high cutoff frequencies suitable for application in mm-wave frequency multipliers. The theory of such frequency multipliers developed by Penfield and Rafuse [1] predicts comparable efficiency for doublers and tripiers, which for available diodes is >50% at 100 GHz. While doublers now approach this ideal when circuit losses are taken into account [2], tripiers have fallen well short of this goal. In this work computer studies have been made to predict the optimum embedding impedances for a mm-wave tripler, and model measurements have accompanied these in order to achieve optimum impedances In an actual unit. This work has resulted in a significant Improvement in tripler efficiency although results are still short of the theory.