Intranasal betamethasone valerate aerosol, given for 28 days, was compared with an oral antihistamine compound in a couble-blind, double-dummy, cross-over trial involving thirty patients with perennial rhinitis. The steroid aerosol was more effective in reducing symptoms and was preferred by the patients (P less than 0-01). Nasal blockage index, calculated from oral and nasal peak expiratory flow measurements, did not provide useful or additional information. There were no side effects from the steroid and Candida albicans was not cultured from nasal swabs. It is concluded that beta-methasone valerate aerosol is a suitable short-term alternative for patients whose perennial rhinitis fails to respond to conventional therapy.