We tested the hypothesis that antihistamine-decongestant combinations cause no clinically significant relief of the symptoms of upper respiratory tract infections in young children by randomly assigning 96 children to one of three treatment groups: antihistamine-decongestant, placebo, and no treatment. There were no differences among the three study groups in the proportion of children considered "better" overall by the parent 48 hours after the initial assessment (drug, 67%; placebo, 71%; no treatment, 57%; p = 0.53). There were no differences among groups in individual or composite symptom score changes. Two thirds of parents whose children were eligible for the drug trial believed that their child needed medicine for cold symptoms. In the proportion of parents believing that their child needed medicine, there was no difference between those who consented to participate and those who refused. Parents who wanted medicine at the initial visit reported more improvement at follow-up, regardless of whether the child received drug, placebo, or no treatment. We conclude that there is no clinically significant improvement in symptoms of upper respiratory tract infection, including no significant placebo effect, in young children for whom an antihistamine-decongestant is prescribed.