There were an estimated 1.66 million hip fractures world-wide in 1990. According to the epidemiologic projections, this worldwide annual number will rise to 6.26 million by the year 2050. This rise will be in great part due to the huge increase in the elderly population of the world. However, the age-specific incidence rates of hip fractures have also increased during the recent decades and in many countries this rise has not leveled off. In the districts where this increase has either showed or leveled off, the change seems to especially concern women's cervical fractures. In men, the increase has continued unabated almost everywhere. Reasons for the age-specific increase are not known: increase in the age-adjusted incidence of falls of the elderly individuals with accompanying deterioration in the age-adjusted bone quality (strength, mineral density) may partially explain the phenomenon. The growth of the elderly population will be more marked in Asia, Latin America, the Middle East, and Africa than in Europe and North America, and it is in the former regions that the greatest increments in hip fracture are projected so that these regions will account for over 70% of the 6.26 million hip fractures in the year 2050. The incidence rates of hip fractures vary considerably from population to population and race to race but increase exponentially with age in every group. Highest incidences have been described in the whites of Northern Europe (Scandinavia) and North America. In Finland, for example, the 1991 incidence of hip fractures was 1.1% for women and 0.7% for men over 70 years of age. Among elderly nursing home residents, the figures can be as high as 6.2% and 4.9%. The lifetime risk of a hip fracture is 16%-18% in white women and 5%-6% in white men. At the age of 80 years, every fifth woman and at the age of 90 years almost every second woman has suffered a hip fracture. Since populations are aging worldwide, the mean age of the hip fracture patients are increasing rapidly, too. Between 1970 and 1991, the mean age of male Finnish patients increased dramatically from 52.9 years to 69.0 years. In women, the corresponding figures were 71.6 and 78.9 years. This change is likely to cause increasing problems in the treatment and rehabilitation of the patients. In 1990, 72% of the hip fractures worldwide occurred in women. All over the world, the hip fracture incidences are about two times higher in women than in men. Women's overrepresentation has been explained by women's lower bone mass and density and higher frequency of falling. Epidemiologic studies show that trochanteric fractures are an increasing problem since compared with cervical fractures their relative number increases progressively with age in women after the age of 60 years and since their incidence has been shown to increase in both sexes and all age groups during the recent decades. This may have direct public health implication since mortality, morbidity, and costs caused by trochanteric fractures are higher than those of the cervical fractures. Reduced bone density (strength) by age and over the recent decades has been the most frequently mentioned reason for the increase of trochanteric fractures. Also, the fall characteristics of the elderly may have changed during the recent decades resulting in increasing numbers of this type of hip fractures since the type of the hip fracture (cervical or trochanteric) also depends on the impact angle of the greater trochanter at the moment of the floor contact.