Introduction: Long bone fracture treatments have always been a serious problem in medicine and until the mid-19th century, fractures were being treated primarily conservatively. The evolution of surgical treatments was greatly influenced by the introduction of anesthetics, antiseptics and X-rays. Intramedullary osteosynthesis (IO) is the youngest surgical technique which showed many advantages in treating long bone fractures compared to other methods. One of those advantages is also the shorter length of hospital stay. Objectives: To examine the average length of hospital stay of patients who underwent IO of humerus, femur and tibia and to determine whether there is a difference in length of stay when taking into consideration gender and age of patients. Study Design: Cross-sectional study Participants and Methods: By examining operational protocols in the General Hospital Nova Gradiška, 63 patients who underwent IO in the period from 2008 to 2018 were found. Furthermore, additional data was gathered from the hospital archive. Variables intended for analysis were as follows: gender, age, diagnosis and length of hospital stay. Results: Out of the 63 cases, 22 pertained to humerus, 18 to femur and 23 to tibia. The mean length of hospital stay for patients who underwent IO of humerus was 9 days, same as for those who had IO of tibia. Those who had IO of femur had a mean length of stay of 14 days. Differences regarding gender were recorded in the case of all three bones, however, they are of no statistical significance. Moreover, there was no statistically significant correlation between the length of hospitalization and age. Conclusion: The length of hospital stay was found to be the longest among patients who underwent IO of femur, whereas patients who underwent IO of tibia and humerus had a similar length of hospital stay.