Objective: Few cost-of-illness studies in stroke have examined the incremental impact of comorbid condition(s). The aim of this study was to assess the costs of stroke management attributable to stroke and comorbid conditions using data from the Medicare program in the United States (U.S.). Methods: Medicare beneficiaries diagnosed with hemorrhagic (HS) and ischemic (IS) stroke from 2002-2005 were identified from a 5% random sample of Medicare outcomes and care database. Direct costs were assessed from the perspective of the Medicare program. Descriptive and multivariate analyses were performed. Data were analyzed from one year prior to the index event through four years following that event. Results: A total of 10,335 patients were identified; 8,444 with IS and 1,891 with HS. Increases in medical costs during the four year post index period were as follows for HS patients: without co-morbidities, $14,745; with hypertension, $22,667; with hypertension plus type 2 diabetes (T2D), $29,662; with hypertension plus congestive heart failure (CHF), $26,768; with hypertension plus T2D plus CHF, $34,302. For IS patients, these costs were $17,000 for IS-only patients, but ranged from $21,344-$30,987 for IS patients with other comorbidities. Results from multivariate analyses supported the validity of the descriptive statistics. Conclusion: Comorbidities/risk factors contribute substantial incremental costs to the already high economic burden of both HS and IS stroke.