AbstractA method for optimizing bends for oversized waveguides using a genetic algorithm is described. A program was developed to optimize the curvature function and – for corrugated waveguides – the corrugation depth of a bend. After a description of the algorithm and its implementation, the results of the optimization of a 28 GHz TE01 bend are shown. Starting with a constant curvature, the algorithm produced a bend with a peak power of spurious modes inside the bend of about 12% and a spurious mode content at the bend end of less than 0.1%. A comparison shows, that the optimized bend is much better than bends of the same size with analytical curvature functions (sin, sin2).