H. Paul A. Illing, Ph.D., F.I.Biol., F.R.S.C., Dip.R.C. Path., is Head of Toxicology in the Medical Division of the Health and Safety Executive, Merseyside, U.K., Dr. Illing studied at Queens College, Dundee (from 1967, University of Dundee) and graduated B.Sc. (St. Andrews) in 1969 and Ph.D. (Dundee) in 1972. Following a period at the University of Mainz (West Germany) as aWellcome Trust/DFG Fellow, Dr. Illing was a Scientist and Senior Scientist in Drug Metabolism and Pharmacokinetics at Hoechst Pharmaceutical Research Laboratories, Milton Keynes, U.K. from 1974 to 1982. Since 1982 he has been at the Health and Safety Executive where he was appointed to his present position in 1986., Dr. Illing is a Fellow of the Institute of Biology and of the Royal Society of Chemistry and holds the Diploma in Toxicology of the Royal College of Pathologists. He is a member of the Biochemical Society, the British Toxicology Society, and the U.K. Environmental Mutagenicity Society., Dr. Illing's interests include methods for studying foreign compound metabolism and the role of such studies in understanding the biological effects of chemicals.