A new topically administered intranasal antiallergic drug, azelastine, was investigated in a large randomized multicenter study that compared it with oral cetirizine from the aspects of efficacy and safety. Patients were treated for 14 days, and efficacy was assessed on days 7 and 14 by means of an investigator rating scale measuring the severity of eight nasal and ocular symptoms of seasonal rhinitis. In addition, patients recorded the extent of individual symptoms on a visual analogue scale (VAS). Tolerability was assessed on the basis of adverse events reported. Data from a total of 129 patients were included in the analysis of drug efficacy. Treatment groups had significant reductions in the investigators' total symptom score during treatment. These reductions were 47% and 55% for azelastine and cetirizine, respectively, at day 7 and 61% and 67% at day 14. There were no differences between the two groups whether they were analyzed overall or separately for nasal and ocular symptoms. Patients' daily VAS scores showed a significantly better resolution of nasal stuffiness and rhinorrhea in the azelastine-treated group than in the cetirizine-treated group. There were no differences for any other symptom. Adverse events were reported by 12 patients in the azelastine group and 20 patients in the cetirizine group. Drowsiness was the only frequently occurring event and this was reported by 9 patients in the cetirizine group and 2 patients in the azelastine group (P = 0.003).