Abstract: To study the efficacy and safety of fexofenadine hydrochloride sustained capsule in treating seasonal allergic rhinitis. Methods: A randomized, doubleblind, doubleanalog comparative multicenter trial was performed on 140 patients, who were randomly given either fexofenadine hydrochloride　(n=71) or cetirizine dihydrochloride　(n=69) one tablet in the morning and one in the night.　After a followup on the 7 th day anthe 14 th day, the efficacy and adverse response were monitored at the end of the 2 weeks. Results: Of the 140 patients, 137 or 140 could be evaluated the efficacy or safety, respectively. The total response rate of fexofenadine hydrochloride and cetirizine dihydrochloride was 66.20% and 68.12%, respectively（P＞0.05）. No statistical difference of the adverse reactions was found between the two groups（P＞0.05）. Conclusion: Both fexofenadine hydrochloride and cetirizine dihydrochloride are well tolerated and effective in the treatment of seasonal allergic rhinitis.

Key words: Hay fever, Clinical trials, Fexofenadine hydrochloride