169 postmenopausal women and 84 male patients aged over 59 years from the outpatient consultations of 32 general practitioners were examined. The most frequently encountered risk factors for osteoporosis were low physical activity (41% of women, 27% of men), low intake of dairy products (37%/21%), smoking (11%/22%), while the particularly relevant risk factors were more rare, such as corticotherapy (7%/9%) and early menopause (17%). The risk factors were not more frequent than in 550 persons of the same age screened among the Swiss general population in another study. The same group of persons also yielded reference values for urinary calcium and hydroxyproline in the fasting urine, which are both considered as markers of bone turnover and as potential tools for screening osteoporosis. The urinary values were independent of age, body mass index, calcium intake, and the duration of the postmenopausal period. They were different from those found in 38 patients with Paget's disease, 66 patients with malignant hypercalcemia and 25 with bone metastasis from breast cancer. Calcium and hydroxyproline excretion are expressed as a ratio of urinary creatinine. Percentiles 10 and 90 of urinary calcium are 0.058 and 0.363 mmol/mmol (male) and 0.062 and 0.523 mmol/mmol (women). Percentiles 10 and 90 for urinary hydroxyproline are 0.006 and 0.024 mmol/mmol (male) and 0.010 and 0.025 mmol/mmol (women).