Ciclesonide is a corticosteroid in development for allergic rhinitis that has been shown to be safe and effective in seasonal allergic rhinitis and perennial allergic rhinitis (PAR) trials of up to 6 weeks in duration. However, the long-term safety and efficacy of ciclesonide are unknown. To demonstrate the long-term safety of intranasal ciclesonide, 200 microg once daily, in patients with PAR. Patients (> or = 12 years old) with a 2-year or longer history of PAR were randomized in a double-blind fashion to receive ciclesonide, 200 microg, or placebo once daily in the morning for up to 52 weeks. Spontaneous and elicited adverse events were monitored throughout the study. Ear, nose, and throat examinations were performed to evaluate local tolerability. Additionally, 24-hour urinary free cortisol level, morning plasma cortisol level, intraocular pressure, and lens opacification were monitored to evaluate the systemic safety of intranasal ciclesonide. Ciclesonide efficacy was determined by measuring 24-hour reflective total nasal symptom scores. No clinically relevant differences were observed between the ciclesonide and placebo groups in adverse events, ear, nose, and throat examinations, or 24-hour urinary free or morning plasma cortisol levels. Similarly, no clinically relevant differences were found between treatment groups in intraocular pressure, visual acuity, or lens opacification. With regard to efficacy, ciclesonide achieved a significantly greater reduction in 24-hour reflective total nasal symptom score compared with placebo over more than 52 weeks (P < .001). In this study, intranasal ciclesonide, 200 microg once daily, was safe and effective for the long-term treatment of PAR, with no evidence of tachyphylaxis.