It was not so long ago when the state of the art in bioremediation was represented by the manipulation of biodegradation by aerobic micro-organisms. Initial technologies included landfarming using rotavation of treatment beds dosed with inocula and nutrients intended to support biodegradation, or the injection of hydrogen peroxide into the subsurface to provide oxygen to in situbiodegradation. The technology, its rationale and its application have since come a long way. Initially regarded with deep scepticism by the remediation fraternity, advances in fundamental knowledge have shifted the bioremediation paradigm, and ultimately resulted in a wide range of practical solutions now in general use. This brief look back highlights some of the key developments that have ushered in modern bioremediation, able to deal with problems thought untreatable just 25 years ago. The intention of this presentation is to provide a basic microbiological perspective, in particular for those from other disciplines involved in contaminated site management.