43 children who presented with angio-oedema and/or urticaria and who responded to an additive-free diet were challenged with artificial food additives in a double-blind study. 24 children reacted to 1 or more of the additives. 18 children did not react to any additives and remained well when a normal diet was re-introduced. Aspirin sensitivity was found in only 1 of the 24 children who could not tolerate additives. Atopy was less common in these patients than in the general population. The mechanism of additive intolerance is unknown and double-blind challenge is the only reliable means of diagnosis.