Pathological bone changes affect locomotor activity and may influence the outcome and prognosis of Parkinson's disease (PD). In this study, we determined the relationship between bone changes and PD. Bone study was performed by multiple scanning x-ray photodensitometry (MD/MS) in 64 patients with PD and 42 age-matched controls. We then compared the results with the clinical characteristics of PD. Osteopenia was detected in 22 (53.6%) of the 41 female and 6 (26%) of the 23 male patients, and in 6 (26%) of the 23 female and 2 (10.5%) of the 19 male controls. The frequency of osteopenia was significantly greater in the female patients than in the male patients or the female controls. Osteopenia was related to the duration of PD in the men, but not in the women. Twenty of 40 PD patients' hands showed side-related differences in the analysis of both hands. In 19 of the 20 patients, the side of more severe osteopenia coincided with that of parkinsonian symptoms, suggesting that osteopenia is related to the pathophysiology of PD.