The proceedings of the NATO Advanced Research Workshop on Biological Electron Transfer Chains contains reports on three themes. The first theme concerns electron transfer. The analysis of ET at the molecular level is still fundamental to an understanding of how ET chains operate in vivo. The second theme concerns bacterial redox chains. These contributions show how complicated these chains can be, often involving a number of gene clusters, each of which in turn consists of an extensive array of genes. The third theme relates to the structure and function of redox proteins. Structural...