A double-blind non crossover trial comparing disodium cromoglycate (DSCG), with ketotifen, was carried out in twenty-seven extrinsic asthmatic children over 12 weeks. Assessment was made using symptom score and drug score charts. Both drugs showed a similar protective effect in the group studied. None of the subjects had to withdraw from the trial and no side-effects were noted in weight-curve, arterial pressure and pulse rate. PEFR values remained unchanged for both drugs throughout the trial. A non-significant tendency for additional corticosteroid support in the Ketotifen group was noted.