Dietary fats and carbohydrates represent some eighty to ninety percent of food energy uptake in man; fatty acids play a critical role in human development, health and disease. In affluent populations high fat consumption contributes to heart disease, obesity and type II diabetes mellitus, while in non-affluent groups, the generally poor nutritional state found in young children can be partially attributed to a low fat intake. This book reviews our current understanding of essential fatty acids and their role in human nutrition. The topics addressed include the analysis of dietary fatty acids, dietary fats and fish oils in health and in the prevention of heart disease, linoleic acid in the treatment of diabetes, and the role of essential fatty acids in early human development.