A double-blind study comparing oxatomide, a new oral drug with anti-allergic properties, with placebo in the treatment of patients with asthma with or without perennial rhinitis has been undertaken. Sixty-two patients were followed up to 28 weeks and fifty-two to 52 weeks. On admission to the study the great majority of the patients were receiving inhaled steroids and about a third sodium cromoglycate for their asthma. The results of the study suggest that oxatomide has some activity but have failed to show that it is substantially better than placebo in this group of patients. For the first time weight-gain is reported as a side effect of oxatomide.