Forty-nine patients participated in a randomized double-blind, parallel group comparison of beclomethasone dipropionate aqueous nasal spray with terfenadine tablets in the treatment of hay fever. Symptom scores for nasal and ocular symptoms as well as grass pollen counts were registered daily for at least 1 month. Evaluation of daily symptom scores and the physicians' and patients' assessments of treatment demonstrated that both treatments were effective in controlling the symptoms of hay fever, with a similar incidence of side-effects. The beclomethasone dipropionate group, in general, had lower nasal symptom scores than the terfenadine group and this reached statistical significance on high pollen count days. In contrast, the terfenadine group had lower eye symptom scores than the other group and these were statistically significant during the first half of the study period. However, the use of additional medication for control of eye symptoms was similar in both groups. It is concluded that treatment with both beclomethasone dipropionate and terfenadine throughout the season was effective in controlling hay fever symptoms, but beclomethasone dipropionate is likely to provide better overall control since it prevented breakthrough of troublesome nasal symptoms during high pollen count days.