This multicentre, randomized, double-blind, parallel-group study was designed to compare the efficacy and tolerability of fluticasone propionate aqueous nasal spray 200 μg once daily (FPANS 200 μg od) with FPANS 200 μg twice daily (bd) in patients whose seasonal rhinitis symptoms were not completely controlled with FPANS 200 μg od. A total of 549 patients initially received FPANS 200 μg od during the open-treatment phase of the study. After 2 weeks, 65% of patients had their symptoms well controlled by FPANS 200 μg od and continued with this treatment for a further 2 weeks. The remainder received either FPANS 200 μg od or FPANS 200 μg bd for a further 2 weeks. Efficacy was evaluated by the analysis of symptom-free days. In the uncontrolled group, there was a significant increase in the percentage of symptom-free days in the FPANS 200 μg bd group over the FPANS 200 μg od group for nasal blockage on waking (P<0.05) and nasal blockage during the day (P<0.05). Similar trends were observed for sneezing, rhinorrhoea, nasal itching, and eye symptoms. There was a significant increase in the percentage of days with a symptom score of less than 2 in the FPANS 200 μg bd group for nasal blockage during the day (P < 0.05). Adverse events were similar in nature and frequency in each treatment group. It is concluded that in the majority of patients symptoms of seasonal rhinitis are well controlled by FPANS 200 μg od. In the minority of patients whose symptoms are not adequately controlled by a once daily dose, FPANS 200 μg bd provides additional relief, particularly from nasal blockage.