Between 1988 and 1991, the relation between leisure time physical activity, bone mineral density (BMD), and osteoporotic fracture was evaluated in a cohort of community-dwelling California adults (1,014 women and 689 men) with a mean age of 73 years. By means of a modified Paffenbarger questionnaire, participants were asked to report exercise from the past year and to recall their level of exercise during three other periods: the teenage years, age 30 years, and age 50 years. The survey asked the number of times strenuous (e.g., jogging), moderate (e.g., fast walking), or mild (e.g., golfing) exercise was undertaken in an average week. A summary score was constructed to represent lifetime exercise. Analysis of the exercise-fracture and exercise-BMD associations were performed using logistic and linear regression analyses, respectively. Linear regression models were controlled for age, body mass index, sex, diagnosis of arthritis, dietary calcium intake, and use of cigarettes, alcohol, thiazides, and estrogen (women only). No association between current or former exercise and BMD at the radius, wrist, or spine was found. A positive association between current exercise and BMD was found at the total hip (p = 0.001) and at each hip component--greater trochanter (p = 0.02), intertrochanter (p = 0.001), and femoral neck (p = 0.02). Mean hip bone densities of strenuous (p = 0.004) and moderate (p = 0.004) current exercisers were higher than those of mild or less than mild exercisers. Lifetime exercise was also positively associated with BMD of the total hip (p = 0.008) and hip components, and demonstrated a borderline-significant association (p = 0.06) with spine BMD. At the hip, each pairwise comparison between the highest and lowest tertiles of lifetime exercise showed a significant difference (p < or = 0.007). Exercise was unassociated with minimal trauma fracture occurring at any site between 1972 and 1991. These data suggest a protective effect of current and lifelong exercise on hip BMD, but not on osteoporotic fracture, in older men and women.