Context: Low 25-hydroxyvitamin D [25(OH)D] and high PTH may contribute to increased mortality risk in older adults. Objective: The aim of the study was to test the association between 25(OH)D, PTH, and mortality in older men. Design and Setting: The prospective Osteoporotic Fractures in Men (MrOS) study was conducted at six U.S. clinical centers. Participants: We studied community-dwelling men at least 65 yr old (n = 1490). Main Outcome Measure: Multivariate-adjusted proportional hazards models estimated the hazard ratio (HR) for mortality; cause of death was classified as cancer, cardiovascular, and other by central review of death certificates. Results: During 7.3 yr of follow-up, 330 (22.2%) participants died: 97 from cancer, 110 from cardiovascular disease, and 106 from other causes. The adjusted HR per SD decrease in 25(OH)D for all-cause mortality was 1.01 (95% CI, 0.89, 1.14); no association between 25(OH)D and cardiovascular or other-cause mortality was seen. Unexpectedly, lower 25(OH)D levels were modestly associated with a decreased risk of cancer mortality (adjusted HR per SD decrease, 0.80; 95% CI, 0.64, 0.99). Analyzing 25(OH)D as a categorical variable did not alter these results. Higher PTH levels (log-transformed) were associated with an increased risk of all-cause mortality (adjusted HR per SD increase, 1.15; 95% CI, 1.03, 1.29) and cardiovascular mortality (adjusted HR per SD increase in PTH, 1.21; 95% CI, 1.00, 1.45). Conclusions: In contrast to previous studies, lower 25(OH)D levels were not associated with an increased risk of all-cause or cause-specific mortality in older men. Higher PTH levels were associated with a modest increase in mortality risk. Copyright © 2010 by The Endocrine Society.