C-reactive protein (CRP) increases following an acute stroke/transient ischemic attack (TIA), but the increment level varies among patients. We analyzed CRP concentrations during an acute stroke/TIA in relation to the CRP gene -717A>G polymorphism. Six months following an acute ischemic stroke/TIA, basal concentrations of CRP were measured in 507 controls and 219 patients and were found to be unassociated with the CRP -717A>G polymorphism. However, during the acute phase of stroke/TIA, individuals with the AG/GG genotype had significantly elevated CRP concentrations as opposed to those with the AA genotype (2.02 +/- 1.59 vs. 1.73 +/- 1.69 mg/l, P = 0.027). In addition, significant 3.22-fold increments in CRP concentrations was noted in individuals carrying the -717G allele when comparing the acute phase with the basal state of each patient and averaging the results. CRP -717A>G polymorphism is associated with triggered CRP concentrations during acute stroke/TIA. These findings might shed more light on the mechanisms of CRP elevation in acute ischemic stroke/TIA.