Eighty patients with atopic eczema were treated with various elimination diets. Some or all foods were withdrawn then later reintroduced singly to the diet. In four patients reintroduction of a single food (soya, chicken, corn, cows' milk) caused anaphylactic shock. In two patients spontaneous recovery occurred but in two resuscitation and intensive care were required. Anaphylaxis is a definite hazard of these elimination diets. Other than warning the parents, practical precautions are difficult because of the unpredictability of violent reactions and uncertainty about the life saving efficacy of injected adrenaline.