This new edition of a highly successful text, published in its second edition in 1981, adheres to the framework laid down by the late Professor Underwood, but has been thoroughly revised by Dr. Neville Suttle. It begins with three chapters of general introduction on the physiological need for minerals, dietary sources of minerals and the principles governing detection of deficiencies. Several advances in the assessment of mineral availability are described and claims for enhanced availability for new chelated sources critically reviewed. The chapter on detection includes new physiological and biochemical definitions of the marginal band between a deficient and normal mineral status to improve the precision of diagnoses. In bringing the chapters on macro-minerals up-to-date, calcium and phosphorus are treated separately to acknowledge their distinctive metabolism outside the skeleton and new treatments, such as the use of acid diets for milk-fever, are described. The contrasting features of phosphorus and magnesium nutrition in the ruminant and non-ruminant are drawn out and the unique need of the ruminant for elemental sulphur is stressed in a new chapter. With trace elements, a few chapters (e.g. iron and manganese) show relatively little change from the second edition while others have changed drastically: for example, the identification of new seleno-proteins with hitherto unknown functions and a new interaction (with iodine) necessitate a major revision of the selenium chapter. A new chapter has been introduced to cover the newer essential trace elements, notably chromium. Coverage of toxic elements has been extended to include common dietary poisons such as arsenic and lead as well as fluorine. The edition concludes with a new chapter on the improved conduct and interpretation of supplementation trials which reflects their important role in differential diagnosis. Easy reference appendix tables summarize essential information in feed composition, dietary requirements and criteria of mineral status in livestock. The book will continue to represent a concise text on this important topic for advanced students of animal science.