The Mediterranean diet has been widely promoted and may be associated with chronic disease prevention and a better overall health status. The aim of this study was to evaluate whether the Mediterranean diet score inversely predicted total or cause-specific mortality in a prospective population study in Northern Sweden (Västerbotten Intervention Program). The analyses were performed in 77,151 participants (whose diet was measured by means of a validated FFQ) by Cox proportional hazard models adjusted for several potential confounders. The Mediterranean diet score was inversely associated with all-cause mortality in men [HR = 0.96 (95% CI = 0.93, 0.99)] and women [HR = 0.95 (95% CI = 0.91, 0.99)], although not in obese men. In men, but not in women, the score was inversely associated with total cancer mortality [HR = 0.92 (95% CI = 0.87, 0.98)], particularly for pancreas cancer [HR = 0.82 (95% CI = 0.68, 0.99)]. Cardiovascular mortality was inversely associated with diet only in women [HR = 0.90 (95% CI = 0.82, 0.99)]. Except for alcohol [HR = 0.83 (95% CI = 0.76, 0.90)] and fruit intake [HR = 0.90 (95% CI = 0.83, 0.98)], no food item of the Mediterranean diet score independently predicted mortality. Higher scores were associated with increasing age, education, and physical activity. Moreover, healthful dietary and lifestyle-related factors additively decreased the mortality likelihood. Even in a subarctic region, increasing Mediterranean diet scores were associated with a longer life, although the protective effect of diet was of small magnitude compared with other healthful dietary and lifestyle-related factors examined.