Background Studies indicate adherence to biologics among patients with psoriasis is low, yet little is known about their use in the Medicare population. Objective We sought to investigate real-world utilization patterns in a national sample of Medicare beneficiaries with psoriasis initiating infliximab, etanercept, adalimumab, or ustekinumab. Methods We conducted a retrospective claims analysis using 2009 through 2012 100% Medicare Chronic Condition Data Warehouse Part A, B, and D files, with 12-month follow-up after index prescription. Descriptive and multivariate analyses were used to examine rates of and factors associated with biologic adherence, discontinuation, switching, and restarting. Results We examined 2707 patients initiating adalimumab (40.0%), etanercept (37.9%), infliximab (11.7%), and ustekinumab (10.3%); during 12-month follow-up, 38% were adherent and 46% discontinued treatment, with 8% switching to another biologic and 9% later restarting biologic treatment. Being female and being ineligible for low-income subsidies were associated with increased odds of decreased adherence. Outcomes varied by index biologic. Limitations Patient-reported reasons for nonadherence or gaps in treatment are unavailable in claims data. Conclusion Medicare patients initiating biologics for psoriasis had low adherence and high discontinuation rates. Further investigation into reasons for inconsistent utilization, including exploration of patient and provider decision-making and barriers to more consistent treatment, is needed.