Keywords: dietary quality, dietary patterns, lifestyle factors, smoking, physical activity, elderly, mortality, Mediterranean Diet Score, Healthy Diet Indicator, healthy ageing, self-rated health, functional statusThe contribution of diet and lifestyle factors to healthy ageing was investigated in European elderly, born between 1913 and 1918, of the SENECA study. First, the Mediterranean Diet Score (MDS), Healthy Diet Indicator (HDI), and cluster analysis were validated as measures of quality of dietary patterns in the SENECA study as well as the Framingham study. Cluster analysis, MDS, and HDI showed strong similarities in the classification of persons into dietary quality groups. High-quality diets were associated with nutritional status and health-related indicators. It is concluded that dietary quality can be assessed using diet scores as well as cluster analysis, the approaches being complementary.The relationships of the three lifestyle factors diet, physical activity, and smoking habits to survival and maintenance of health at old age were investigated, using Cox's proportional hazards analysis and logistic regression. Single unhealthy lifestyle behaviours were related to an increased mortality risk. For men, the mortality risk for a low-quality diet was 1.2 (95 percent confidence interval (CI): 0.9, 1.7), for inactivity 1.4 (95% CI: 1.1, 1.7), and for smoking 2.1 (95% CI: 1.6, 2.6). For women, the mortality risk for smoking was 1.8 (95% CI: 1.1, 2.7), for inactivity 1.8 (95% CI: 1.3, 2.4), and for a low-quality diet 1.3 (95% CI: 0.9, 1.8). The risk of death was increased for all combinations of two unhealthy lifestyle behaviours. Men and women with three unhealthy lifestyle behaviours had a three to four-fold increase in mortality risk. Self-rated health and functional status both declined in men and women with healthy and unhealthy lifestyle habits over a 10-year follow-up period, but the deterioration in health was delayed by the healthy lifestyle behaviours, non-smoking and physical activity. Inactive ...