There are a number of ways in which food can influence behaviour, including malnutrition, types of diet, eating habits, pharmacological effects, food allergy, fatty acid deficiency and possibly food additives. The range of behaviour affected is also wide, and includes attention, conduct disorder and mood. A particular focus of interest has been the effects of food on hyperactivity in children. There is some initial evidence that fatty acids may influence hyperactivity in children with specific learning disabilities. The findings also suggest that some food additives (colourings, flavourings and preservatives) may increase hyperactivity in children with behaviour problems. For children showing behaviour problems such as hyperactivity the use of dietary manipulation tends to be a more acceptable approach to treatment than the use of drugs. However, there needs to be awareness of the dangers of the use of unsupervised restriction diets with children, and the use of dietary treatments alone is not likely to be sufficient treatment for many children with attention-deficit hyperactivity disorder. A study is currently underway to investigate the possible effects of additives on behaviour in the general population of children.