This volume is devoted to the research area regarding the biological properties of metal alkyl derivatives, offering an authoritative account of this subject by 16 scientists. In 11 chapters, Biological Properties of Metal Alkyl Derivatives highlights, in detail, derivatives of germanium, tin, lead, arsenic, antimony, selenium, tellurium, cobalt (vitamin B12 derivatives) and nickel (coenzyme F430), including the role of (mainly) micro-organisms in their formation. The derivatives of indium, thallium, bismuth, various transition metals and mercury are also covered to some extent, as are those of the non-metals silicon, phosphorus and sulfur, and the haloperoxidase route of the biogenesis of halomethanes by fungi and plants. The properties of these alkyl derivatives, their biosynthesis, including mechanistic aspects, their appearance in waters (rivers, lakes, oceans) and sediments, and their physiological and toxic effects are summarized.