A dramatic progressive increase in the incidence of cervical and trochanteric fractures of the proximal end of the femur was observed in Göteborg from 1940 to 1983. From 1965 through 1983, the fracture rate increased by 109%. Only 20% of the increase can be explained by the age factors in the population. With the present trend, which appeared to be validated by the observed fracture rate from 1981 to 1983, the fracture incidence would double in 16 years in men and in 30 years in women.