Proceedings of the Fourth International Symposium on Insulin, IGFs, and their receptors, held in Woods Hole, Massachusetts, April 1993, under the auspices of the American Diabetes Association. The study of the insulin-like growth factor (IGF) family has become an exciting area of investigation. Among the topics in 38 papers: structure, expression, and regulation of the IGF-I gene; the insulin receptor family; cellular actions of IGF binding protein-3; metabolic effects of rhIGF-I in normal human subjects; IGFs and muscle differentiation; and characterization of the IGF regulatory system in bone.