This investigation examined the associations between exercise habits, measures of physical fitness, and 10-year cardiovascular disease risk (CVD10, expressed as %) among 470 law enforcement officers of differing ages (range = 21 to 63 y). Only 32% of this group exercised regularly (≥3 days/week, ≥20 min/session, ≥preceding 4 weeks). Only exercising subjects >48 years old exhibited a significantly (P < .01) lower 10-year risk of a CVD event than their inactive peers (12.2 ± 5.6 vs 16.3 ± 6.9%, mean ± SD). At all ages, the peak oxygen consumption per unit time was higher (50.1 ± 6.7 vs 44.8 ± 6.1 mL.kg−1.min−1) in the exercising than in the nonexercising group. Exercising subjects ≤36 years old were significantly (P < .05) leaner than nonexercisers (16.3 ± 5.5 vs 19.6 ± 5.5% body fat, respectively) and had greater muscular endurance (45 ± 9 vs 40 ± 9 60s sit-ups, respectively). These data suggest that exercise reduces CVD risk by modifying major CVD risk factors only in law enforcement officers >48 years old.