This book is the published proceedings of the Sixth International Symposium on Trace Element Metabolism in Man and Animals. The Symposium was held at the Asilomar Conference Center in Pacific Grove, California, U.S.A. from May 31 through June 5, 1987. The decision to hold TEMA-6 at Asilomar was made at TEMA-5 in 1985. The International Guidance Committee decided to hold the meeting in California in part to recognize the significant cont~i butions made to the field of trace element metabolism by Professor Lucille S. Hurley. As such, she was the obvious choice as chair of the local organ izing committee. One of the principal goals of Professor Hurley was that TEMA-6 serve as a forum for discussing the use and application of newer methodologies, such as molecular biology, computer modelling and stable isotopes, in studies of trace element metabolism. Based on the comments which the local organizing committee has received, this goal was achieved. The Symposium was attended by 275 scientists from 32 countries covering 6 continents. Twenty-five speakers were chosen for our plenary sessions.