Otolaryngologists and general practitioners commonly prescribed intranasal corticosteroid drops for rhinitis. Compliance in real patients has not previously been studied, but is generally believed to be poor. Recent concerns over systemic adverse effects of topical corticosteroids have highlighted the risks of overdosing. Fifty patients, who were prescribed betamethasone, were prospectively studied for accuracy of compliance using a weighed dose study. Patients consistently administered inaccurate quantities of nasal corticosteroid drops, with a marked tendency to overdose up to four times the recommended daily dose (RDD) in some cases. The mean dose administered was 200 per cent of the RDD. Of the 50 patients, only seven (14 per cent) administered the correct dose. The introduction of metered-dose delivery systems should be considered to reduce the risk of inadvertent overdosing.