PURPOSE: Radial nerve is closely in contact with the bone in sulcus nervi radialis (SNR). Location of SNR shows ethnic differences. Radial nerve is a big problem in humerus fractures and its surgery. In this study, we aimed to examine if humerus fractures of this region increases the probability of radial nerve injury. METHODS: Total length of humerus and the distance of SNR to proximal and distal anatomical points were measured on 57 human dry cadaver bones. The mean values of these data were calculated. The 58 cases of treated humerus fractures in our orthopedics department, whose radiological film techniques were available, were involved in the study and their measurements were made at the same anatomic reference points, retrospectively. Proximal and distal safe zones to total length ratios of both groups were determined. The ratios of the cases were compared with the confidence intervals of dry bones. Location of the fracture line according to SNR and the relationship between radial nerve injury and this location were evaluated. RESULTS: Sulcus nervi radialis region was located at the middle of humerus. Of 24 cases which had radial nerve injury, only nine cases had fracture of SNR region. Of the 34 cases which had no radial nerve injury, 16 had fracture of SNR region. CONCLUSIONS: As a result; radial nerve injury rate was 37.5% for the fractures of SNR region and it was higher compared to other studies. We concluded that the fractures of SNR region do not increase the risk of radial nerve injury.