ObjectiveThe primary aim of the Perindopril Protection Against Recurrent Stroke Study (PROGRESS) is to determine the effects of a long-term angiotensin converting enzyme (ACE)-inhibitor-based blood-pressure-lowering regimen on the risk of stroke among patients with a history of stroke or transient ischaemic attack (TIA). Secondary aims include investigation of the effects of treatment on total cardiovascular events, dementia and disability.Design and methodsPROGRESS is a double-blind, placebo-controlled randomized trial. Patients were randomly assigned to treatment with the ACE inhibitor perindopril (and the diuretic indapamide for those with no definite indication or contraindication to treatment with a diuretic) versus matching placebo(s). Both hypertensive and non-hypertensive patients were eligible for inclusion. Follow-up is scheduled for completion in 2001. The study is being conducted in 172 centres in 10 countries (Australia, Belgium, China, France, Italy, Ireland, Japan, New Zealand, Sweden and the United Kingdom).ResultsRecruitment was completed in November 1997, with 6105 patients randomized. Mean age of participants at study entry was 64 years, 30% of whom were female, 84% had an entry diagnosis of stroke, and the remainder had an entry diagnosis of TIA alone. Mean baseline blood pressure was 147/86 mmHg, with about half the patients reporting current drug treatment for hypertension. At randomization, 58% of patients were assigned to combination treatment with both study drugs versus placebos, and 42% were assigned to perindopril alone versus placebo.ConclusionsThe successful completion of recruitment, together with current indicators of statistical power, suggest that PROGRESS should achieve its primary aim on schedule.