The efficacy of the second generation antihistamine ebastine has been investigated in the treatment and prevention of seasonal allergic rhinitis (SAR). In a double-blind randomised study, patients treated with a single daily dose of ebastine 10mg (n = 116) for 2 weeks showed a significant improvement in symptoms of SAR compared with those treated with placebo (n = 85). Sneezing, rhinorrhoea, tears and conjunctival irritation were all significantly improved, but not blocked nose. The overall efficacy of treatment was judged to be significantly superior in the ebastine group. There was no increase in bodyweight at the end of the study in either of the groups. There was no increase bodyweight at the end of the study in either of the groups. The percentage of patients reporting adverse events were headache, somnolence, nausea, dry mouth, stomach upset and increased appetite. The efficacy of ebastine 10 mg/day (n = 111) was similar to that of astemizole 10 mg/day (n = 106) over a 4-month period in preventing the symptoms of SAR in the open randomised study. The efficacy of both drugs in preventing the onset of sneezing, rhinorrhoea, blocked nose and tears was significant, when symptoms were compared with those during the previous year. At the end of the study, the astemizole-treated patients had a significant increase in bodyweight, which was not observed in the ebastine group. The percentage of patients reporting adverse events was significantly greater in the astemizole group (34.9% versus 20.7%; p = 0.02). Thus, ebastine is a useful alternative treatment for seasonal allergic rhinitis. It has also shown efficacy comparable to that of astemizole in the prevention of onset of symptoms of this allergic condition, and appears to be better tolerated than this agent.