Astemizole, a new long acting and non sedative antihistamine, and Terfenadine, an H1 antagonist widely used, were compared in a randomized double-blind study over 4 weeks in 55 patients suffering from hay fever. The clinical symptoms were recorded daily from each patient on a 4-point scale from 0 = none to 3 = severe. After 2 weeks of therapy and at the end, the total clinical score was evaluated and both the investigator and the patient made an overall assessment of the therapeutic effect. Both drugs were effective in reducing nasal and ocular symptoms, but the clinical response tended to be better with Astemizole than Terfenadine. The difference between the two drugs, however, was statistically significant (p less than 0.05) only after 2 weeks of treatment. Some side effects, including drowsiness, were observed with similar incidence in both treatment groups. Astemizole appears to be a simple, effective and safe therapy for hay fever.