A double-blind clinical trial was undertaken to evaluate the efficacy of orally given cromolyn sodium vs that of pacebo in the management of food allergy. Fourteen children, aged 2 to 15 years, with milk allergy and concomitant allergies to one or more foods were given cromolyn or placebo. Eleven had positive intradermal skin reactions or coproantibodies to offending antigens. Treatment was begun while the children were receiving elimination diets; they were challenged with specific antigen only after 48 hours of drug administration. Crossover took place if the initial agent was ineffective. Cromolyn afforded protection in 11 of 13 trials, whereas placebo was effective in only three of nine trials. By chi 2 analysis, the drug's effect was statistically significant.