The objective of this workshop was to examine the nature of plasma membrane electron transport and how this electron transport contributes to growth of cells. The workshop came at a time when the study of the plasma membrane oxidoreductase activity was beginning to attract more widespread attention from researchers working with both plants and animals. The rapid response of c fos and c myc Proto-oncogene to stimulation of plasma membrane redox activity by external oxidants under­ scores a potential role of plasma membrane oxidoreductases in growth control. Other experiments with isolated endosomes in­ dicate emerging roles in endocytosis and lytic processes. Primary attention was focused on trans plasma membrane electron transport which brings about the oxidation of cytosolic, NADH, NADPH or other substrates by electron flow across the plasma membrane to external oxidants including ferric iron, semide­ hydroascorbate or oxygen. A major theme in the workshop was the relation of this electron flow to pH changes of the cytoplasm or the transfer of protons to the external medium. The presence and role of other oxidoreductases in the plasma membrane was documented, especially in regard to peroxide production. In plant cells this may contribute to cellular defense against invading para­ sites. A corresponding function in animals has been long known and extensively discussed but was beyond the scope of this workshop.