Background: Indexes of diet quality have been shown to be associated with decreased risk of mortality in several countries. It remains unclear if the Alternative Healthy Eating Index (AHEI), designed to provide dietary guidelines to combat major chronic diseases, is related to mortality risk. OBJECTIVE: We aimed to examine the association between adherence to the AHEI and cause-specific mortality over 18 y of follow-up in a British working population. Design: Analyses are based on 7319 participants (mean age: 49.5 y; range: 39-63 y; 30.3% women) from the Whitehall II Study. Cox proportional hazards regression models were performed to analyze associations of the AHEI (scored on the basis of intake of 9 components: vegetables, fruit, nuts and soy, white or red meat, trans fat, polyunsaturated or saturated fat, fiber, multivitamin use, and alcohol) with mortality risk. Results: After potential confounders were controlled for, participants in the top compared with the bottom third of the AHEI score showed 25% lower all-cause mortality [hazard ratio (HR): 0.76; 95% CI: 0.61, 0.95] and >40% lower mortality from cardiovascular disease (CVD; HR: 0.58; 95% CI: 0.37, 0.91). Consumption of nuts and soy and moderate alcohol intake appeared to be the most important independent contributors to decreased mortality risk. The AHEI was not associated with cancer mortality or noncancer/non-CVD mortality. Conclusion: Our findings suggest that the encouragement of adherence to the AHEI dietary recommendations constitutes a valid and clear public health recommendation that would decrease the risk of premature death from CVD.