For more than 50 years EPR spectoscopists have worked predominantly with the standard X-band microwave frequency of 9-10 GHz. Technical developments now make it possible to do experiments on randomly-orientated samples using much higher microwave frequencies and corresponding magnetic fields. For transition ion complexes this can not only result in drastically increased spectral resolution, but it also allows for the spectroscopy of high-spin systems that are undetectable in X-band due to large zero-field interactions. In practice these new possibilities are limited by a concentration sensitivity that decreases with increasing microwave frequency.