Genetic algorithms (GAs) have emerged as an effective adaptive search techniques based on the concept of natural selection. The power of GAs in optimisation has become apparent from the wide range of applications identified in the areas of automatic and adaptive control, but only a few authors have reported on their application to the optimisation of electromagnetic structures. In this paper, we review our continuing work on the application of genetic algorithms to the optimised design of multi-element adaptive antenna arrays and both passive and active wideband radar absorbers. In particular, we present new results for the case of an end-fire array antenna with both adaptive nulling and radiation pattern envelope limitations applied and for the case of wideband high performance cylindrical radar absorbers.