Background: Allergic rhinitis was recently classified by the ARIA guidelines as persistent or intermittent. Levocetivizine was shown to improve symptoms and health-related quality of life of patients with persistent allergic rhinitis in the XPERT™ study, a 6-month randomized double blind placebo-controlled trial. Objective: To assess the total costs of persistent allergic rhinitis, and the effect of long-term treatment with levocetirizine on these costs from several perspectives (societal, social security system, and employers). Methods: Direct medical cost parameters (medications, physician visits and hospitalizations) and time lost parameters (workdays and Usual Daily Activities (UDA) lost) related to persistent allergic rhinitis and its comorbidities (asthma, sinusitis, otitis and upper respiratory infection) were measured. A cost analysis was performed using 2002 French costing data. Results: From a societal perspective, the total cost of persistent allergic rhinitis without long-term treatment was estimated at €355.06/patient/month. From a social security perspective, levocetirizine treatment yielded an additional cost of €2.78/patient/month, compared to no-treatment. However, levocetirizine reduced the total cost of persistent allergic rhinitis and its comorbidities by €152.93/patient/month from a societal perspective and by €64.70/patient/month from an employer perspective. Most gains resulted from a decrease in the lost workdays and UDA in the levocetirizine group. Conclusion: The cost of persistent allergic rhinitis is substantial. Treatment with levocetirizine reduces the cost of persistent allergic rhinitis and its comorbidities to the society by €152.93/patient/month while improving symptoms and health-related quality of life. Copyright © Blackwell Munksgaard 2005. Chemicals / CAS: cromoglycate disodium, 15826-37-6, 16110-51-3, 93356-79-7, 93356-84-4; levocetirizine, 130018-77-8; prednisolone, 50-24-8; Cetirizine, 83881-51-0; Histamine H1 Antagonists, Non-Sedating; levocetirizine, 130018-77-8; Piperazines