Children are often exposed to injuries due to their hyperactivity. Femur fractures can however leave permanent consequences despite adequate treatment. The high prevalence and possible invalidity justify research in the field of prevention of this injury. But prevention is possible only by knowing the causes and circumstances of the fractures. The aim of this research is to analyze the circumstances and places of occurrence in femur fractures according to children age groups. This retrospective study includes 103 children up to the age of 18 years treated at the University Hospital Center of Medicine Zagreb, or at the Clinic for children diseases Zagreb in the period from 2012 to 2016. The study includes 35 (33 %) girls and 71 (67 %) boys, a total of 106 children with femur fractures. The average age was five years. The majority of the injured children, 52 children (55,2 %), belonged to the youngest age group from 0 to 4 years of age. Diaphysis fractures were the most common with 66 fractures (62 %), and the rarest were fractures of the distal metaphysis with 15 fractures (13 %). The fractures occurred at home in 41 cases (38 %), in the street in 38 cases (36 %), at recreation in 22 cases (21 5), and at school or kindergarten in 3 cases (3 %). The most common causes of femur fractures were falls in 38 cases (57,5 %), motor vehicle accidents in 35 cases (33 %), and crashes and blows in 10 cases (9,5 %). One third of the children with femur fractures had associated injuries, and four fifths of them were caused by motor vehicle accidents. The results of this study show that femur fractures are most frequent in the youngest age groups, and are generally a consequence of accidents at home (mostly falls), seldom in the streets or recreational places. Parents of preschool children should be educated about prevention of falling at their homes, and parents of school children should be educated about the dangers of fractures at recreational places and traffic.