Insect resistant genetically modified (GM) crops may provide a partial substitution technology for chemical pesticides. Those which are available commercially are all based on modified Bacillus thuringiensis (Bt) toxins. It is desirable to have a pool of alternative genes that encode insect control proteins (ICPs) having entirely different modes of action. Various classes of compound have been suggested although most have one or more disadvantages compared with Bt toxins. A pool of alternative ICPs would allow pyramiding of resistance genes, which should have a number of advantages: multifactorial resistance is expected to be more durable, to increase the spectrum of pests targeted and to be more effective. Some of these compounds address concerns about durability, spectrum of activity, reliability, environmental impact and public acceptability of GM crops. More speculative alternative approaches which might remove other key constraints on the transgenic approach to crop protection are discussed. The fundamental research necessary for their development is unlikely to be funded from commercial sources.