OBJECTIVES: To estimate the mean annual cost of the different biological agents licensed for the treatment of patients with moderate to severe plaque psoriasis during the first year of treatment and maintenance, according to the daily clinical practice in Spain. METHODS: Data were obtained from case notes of a sequential patient cohort with psoriasis attending a tertiary referral severe psoriasis service and initiated on biologics for treatment of their psoriasis at least 12 months before to the cut-off date (November 2010). Data on drug usage (dose and dosage, starting and changing dates), that patients have experienced throughout the treatment, were collected To estimate the annual drug cost for each patient, two periods of time were considered in the analysis: first year after initiation of biologic therapy and the year before the cut-off as maintenance period. Specific assumptions regarding the dosage, interruption, or switching to other biological after initiation of treatment were set out. Only the cost of biological agents was considered, regardless of any other associated expenses, dismissing those subjects who have been on therapy less than 3 months before switching to other biological drug. RESULTS: The primary analysis population comprised a total of 760 patients: adalimumab (n=212), etanercept (n=214), infliximab (n=145), and ustekinumab (n=189). These subgroups were comparable in age, gender, weight, type of psoriasis, severity, joint affectation and concomitant diseases prevalence. The mean annual costs were: for adalimumab 13,346.48 € and 12,120.09 €, etanercept 15,268.28 € and 14,420.46 €, infliximab 16,589.67€ and 13,889.49 €, and ustekinumab 18.370,50 € and 15.500,44 €. CONCLUSIONS: The current cost analysis clearly shows that the expenditure associated with the use of adalimumab both, at the initiation of therapy and maintenance, reflects the lowest price charged for a biological drug in patients with moderate to severe plaque psoriasis, in daily clinical practice in Spain.