To improve the knowledge of the current trends in the number and incidence of osteoporosis-related pelvic fractures, patients who were admitted to Finnish hospitals in 1970, 1975, 1980, 1985, 1988, and 1991 for primary treatment of first osteoporotic pelvic fracture were selected from the National Hospital Discharge Register. The overall incidence (per 100,000 inhabitants) of osteoporosis-related pelvic fractures (high energy traumas were excluded) in a population aged 60 years or more was 20 in 1970 and 63 in 1991. The increase was most pronounced in the older age groups (patients aged 80 years or more) and was observed in both sexes. The proportion of these osteoporotic pelvic fractures of all pelvic fractures increased from 18% in 1970 to 52% in 1991. Similarly, the proportion of patients over 60 years of age increased from 28% in 1970 to 62% in 1991. In 1991, 78% of the patients with an osteoporotic pelvic fracture were women. Across the study period, the age-adjusted total incidence of osteoporotic pelvic fractures also increased in both women and men 60 years of age and over. The proportional increase was more pronounced in men. We conclude that the number of osteoporotic pelvic fractures in Finland is increasing more rapidly than can be accounted for by the demographic changes only and that effective preventive measures are urgently needed to control the increasing number of these age-related fractures.