Background exposure to persistent organic pollutants (POPs), lipophilic xenobiotics that accumulate mainly in adipose tissue, has recently emerged as a new risk factor for cardiovascular diseases. This prospective study was performed to evaluate if plasma concentrations of selected POPs predict incident stroke among the elderly. Twenty-one POPs (including 16 polychlorinated biphenyl (PCB) congeners, 3 organochlorine (OC) pesticides, 1 brominated diphenyl ether (BDE), and 1 dioxin) were measured in plasma collected at baseline in 898 participants aged 70 years of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS). Stroke diagnosis was validated by hospital records. During the five year follow-up, 35 subjects developed hospital-treated stroke. After adjusting for known stroke risk factors, most PCBs with 4, 5, or 6 chlorine atoms, p,p'-DDE, trans-nonachlor, and octachlorodibenzo-p-dioxin significantly predicted the risk of stroke. Across quartiles of summary measures of PCBs and OC pesticides, the adjusted ORs were 1.0, 0.8 (95% confidence interval: 0.2-2.5), 1.2 (0.4-3.4), and 2.1 (0.7-6.2) for PCBs and 1.0, 1.2 (0.3-4.2), 2.3 (0.7-6.9), and 3.0 (1.0-9.4) for OC pesticides (P for trend = 0.11 and 0.03, respectively). The adjusted ORs among participants >= 90th percentile of the summary measures were 5.5 (1.7-18.1) for PCBs and 4.0 (1.1-14.6) for OC pesticides; corresponding ORs for those >= 95th percentile were 7.8 (2.1-29.6) and 9.5 (2.3-38.9). Background exposure to POPs may play an important role in development or progression of stroke in the elderly.