QCD corrections to e+ e- --> 4 jets

We report on the next-to-leading order QCD calculation for e+ e- --> 4 jets. We explain some modern techniques which have been used to calculate the one-loop amplitudes efficiently. We further report on the general purpose numerical program ``Mercutio’', which can be used to calculate any infrared safe four-jet quantity in electron-positron annihilation at next-to-leading order.