This was a nested case-control study. Plasma samples were obtained from 6,105 subjects enrolled in the PROGRESS study, The nested case-control study included 1773 patients: 591 were cases (83 hemorrhagic strokes, 472 ischemic strokes, and 36 of unknown type), and 1182 were controls who did not subsequently become cases. Controls satisfying all matching criteria were found for 572 of these cases; 19 were incompletely matched. After the addition of cases who acted as matched controls for other cases and taking account of controls who acted for >1 case, there were 33 cases with 1, 213 with 2, and 345 with 3 matched controls. Altogether, 89 cases served as controls for 1 other case. The data were related to clinical markers of cardiovascular risk on enrollment. The study was designed to determine which of these plasma markers provided an independent measure of risk of recurrent stroke. In addition, the study determined those plasma markers that provided an independent measure of reduction in risk of recurrent stroke by perindopril-based antihypertensive therapy, thereby providing a means to identify those subjects most likely to benefit from such therapy, and conversely, those subjects in whom alternative preventative strategies were required. In addition, plasma markers that predicted risk of recurrent stroke may have indicated novel therapies to prevent this condition.