OBJECTIVES:  Biological drugs have improved the management of moderate to severe psoriasis. Little is known about their drug utilization pattern in daily clinical practice. The aim of this study was to estimate the treatment patterns and drug-related cost among patients with psoriasis who initiated biologic therapy. METHODS:  The data used for this retrospective study was obtained from the health administrative database of Caserta Local Health Authority (1 million inhabitants, South of Italy). The health administrative database of Caserta is a data warehouse integrating information from hospital discharge records, pharmacy records, and ambulatory records. We included in the study all subjects that received at least one dispensing of biological drugs (adalimumab, etanercept, infliximab or ustekinumab) from January 2010 to December 2014. Indication for biological drug treatment was retrieved from therapeutically plan. An incident user was defined as a subject who filled his first prescription (index-date) after 2 years biological drugs-free run-in period. Incident biologic users were categorized according to type of biologic prescribed. Medication use patterns, including switching, were identified during a 1-year follow-up period. RESULTS:  387 subjects treated with biological drugs for psoriasis were identified in the study period. 125 incident users were analyzed. Among these, 56.8% received etanercept as first therapy, 26.4% adalimumab, 9.6% ustekinumab, 7.2% infliximab. In 1-year follow-up period, incident users continued their index biologic with an average time to switch of 138.8 days. Rates of switching, was 8.0%, for all patients. Pharmacy expenditure, calculated as annual average cost/per patient, was higher for the switching cohort than the non-switching cohort (14,210 Euro vs 10, 942 Euro). CONCLUSIONS:  The pharmacy expenditure is highly influenced by switch. Our findings may have implications for real-world practice studies.