For maintenance of bone health during adulthood, weight-bearing exercise is recommended. Cycling is becoming a popular form of exercise for older adults due to reduced impact on weight-bearing joints. Some data suggest that bone mineral density (BMD) is reduced in cyclists due to its low-impact. The purpose of this study was to compare BMD of the spine and proximal femur between 10 male masters runners and 12 cyclists aged 51-76 years using dual energy x-ray absorptiometry. Masters runners had significantly greater BMD of both the total hip (p=0.04) and femoral neck (p=0.01) sites of the non-dominant leg compared to masters cyclists. Similarly, masters runners tended to have greater BMD of the lumbar spine compared to cyclists, but this difference did not reach statistical significance (p=0.053).