Thirty patient with allergic rhinitis sensitized to Parietaria pollen were enrolled in a double-blind clinical trial in order to evaluate whether the addition of nimesulide, a non-steroidal antiinflammatory drug, to standard antihistamine therapy may improve symptom relief. Patients were randomly divided in two groups: one was given terfenadine (120 mg/day) and nimesulide (200 mg/day), the other was given terfenadine (120 mg/day) and placebo. Both treatments lasted 30 days. Clinical efficacy was assessed by physical examination on 1st, 15th, 30th day of treatment, daily self-evaluation of symptom score, and patient's overall judgement at the end of the trial. The group receiving terfenadine + nimesulide reported a significant lower symptom score and gave a better overall evaluation than the group receiving terfenadine + placebo. These results suggest that the addition of nimesulide to antihistamine treatment may be useful to achieve a better relief of symptoms in allergic rhinitis.