OBJECTIVES: A number of therapeutic classes are available to treat psoriatic arthritis (PsA), including biologic drugs. Although the wholesale acquisition cost of biologic drugs has increased in recent years, there is little published evidence documenting cost trends from the US perspective. The objective of this study was to assess cost trends for patients using biologic therapy for PsA from the US perspective.  METHODS: Continuously enrolled adult patients with ≥2 outpatient diagnoses of PsA were selected from the MarketScan databases if their first biologic prescription date (index date) occurred between July 1, 2008, and July 31, 2013. Patients were included in the study if (1) full access was available to all medical and pharmacy claims for ≥6 months before and ≥12 months after their index date, and (2) they were biologic-naïve before index. Healthcare costs were assessed from the payer perspective and based on annual reimbursed amounts. Results were stratified by all-cause vs. PsA-related costs and within these 2 categories further subdivided into medical inpatient, medical outpatient, emergency room, and pharmacy costs.  RESULTS: : In total, 25,565 patients met the inclusion criteria. All-cause healthcare costs in the 6 annual cohorts increased by 53.1% between 2008 and 2013, with an average annual increase of 10.6% (or $2,867). PsA-related annual costs were estimated to increase by 63.6%, with an average annual increase of 12.7% (or $2,335). Although cost increases in all categories of interest were observed over time, the major driver of the observed trends was the PsA-related pharmacy costs, predominantly the cost of biologic therapy, with an estimated increase of 65.6% and an average annual increase of 13.1% (or $2,220). CONCLUSIONS: For US managed care payers, total healthcare costs among patients initiated on biologic therapy for PsA has increased by 53.1%, which is mostly driven by the 65.6% change in PsA-related pharmacy costs.