BACKGROUND: Our aim was to investigate whether a nurse-coordinated multidisciplinary, family-based preventive cardiology programme could improve standards of preventive care in routine clinical practice. METHODS: In a matched, cluster-randomised, controlled trial in eight European countries, six pairs of hospitals and six pairs of general practices were assigned to an intervention programme (INT) or usual care (UC) for patients with coronary heart disease or those at high risk of developing cardiovascular disease. The primary endpoints-measured at 1 year-were family-based lifestyle change; management of blood pressure, lipids, and blood glucose to target concentrations; and prescription of cardioprotective drugs. Analysis was by intention to treat. The trial is registered as ISRCTN 71715857. FINDINGS: 1589 and 1499 patients with coronary heart disease in hospitals and 1189 and 1128 at high risk were assigned to INT and UC, respectively. In patients with coronary heart disease who smoked in the month before the event, 136 (58%) in the INT and 154 (47%) in the UC groups did not smoke 1 year afterwards (difference in change 10.4%, 95% CI -0.3 to 21.2, p=0.06). Reduced consumption of saturated fat (196 [55%] vs 168 [40%]; 17.3%, 6.4 to 28.2, p=0.009), and increased consumption of fruit and vegetables (680 [72%] vs 349 [35%]; 37.3%, 18.1 to 56.5, p=0.004), and oily fish (156 [17%] vs 81 [8%]; 8.9%, 0.3 to 17.5, p=0.04) at 1 year were greatest in the INT group. High-risk individuals and partners showed changes only for fruit and vegetables (p=0.005). Blood-pressure target of less than 140/90 mm Hg was attained by both coronary (615 [65%] vs 547 [55%]; 10.4%, 0.6 to 20.2, p=0.04) and high-risk (586 [58%] vs 407 [41%]; 16.9%, 2.0 to 31.8, p=0.03) patients in the INT groups. Achievement of total cholesterol of less than 5 mmol/L did not differ between groups, but in high-risk patients the difference in change from baseline to 1 year was 12.7% (2.4 to 23.0, p=0.02) in favour of INT. In the hospital group, prescriptions for statins were higher in the INT group (810 [86%] vs 794 [80%]; 6.0%, -0.5 to 11.5, p=0.04). In general practices in the intervention groups, angiotensin-converting enzyme inhibitors (297 [29%] INT vs 196 [20%] UC; 8.5%, 1.8 to 15.2, p=0.02) and statins (381 [37%] INT vs 232 [22%] UC; 14.6%, 2.5 to 26.7, p=0.03) were more frequently prescribed. INTERPRETATION: To achieve the potential for cardiovascular prevention, we need local preventive cardiology programmes adapted to individual countries, which are accessible by all hospitals and general practices caring for coronary and high-risk patients.