The effects of prolonged treatment with intranasally applied budesonide was studied in twenty-four patients with perennial allergic or non-allergic rhinitis. Patients on continuous treatment were followed up for 5.5 years. At entry and follow-up visits, rhinoscopic findings, nasal symptom scores, blood chemistry, haematology, urine analysis and determination of plasma cortisol levels, before and after stimulation with ACTH (Synacthen, Ciba-Geigy AG, Basel, Switzerland), were registered. Biopsies of the nasal mucosa were taken before entry into the study, after 1 year of treatment, and after varying time intervals ranging from 2.5 to 5.5 years during the treatment. The biopsy specimens were examined blindly by an independent pathologist. The analyses revealed no histopathological changes in the nasal mucosa. All nasal symptom parameters assessed by the patients were significantly reduced from the baseline during the entire follow-up period. No clinically significant changes in the haematological and blood chemistry parameters were observed. Plasma cortisol analyses before and after challenge with ACTH revealed no influence on the hypothalamic pituitary adrenal (HPA) axis. The present study suggests that intranasal budesonide in the dose of 200-400 micrograms/day is also a safe treatment for prolonged treatment of perennial rhinitis.