OBJECTIVE In this study, we retrospectively evaluated patients with isolated diaphyseal radius fractures treated with plates or IMNs and compared their radiological and functional results. METHODS 49 patients who met the criteria were included in the study. Of these, 22 were treated with plate osteosynthesis and 27 with IMNs. The mean age of plate group was 36.8 (range 17-68), IMN group was 34.3 (range 18-74). 39 (79.6%) of the patients were males and 10 (20.4%) were females. The mean follow-up period was 26 (range 12-48) months. RESULTS The mean union time was 12.1 ± 0.9 weeks in the IMN group and 12.2 ± 1.2 weeks in the plate group. Union was achieved in all patients in the IMN group (100%) and in 21 of 22 patients in the plate group (95.4%). The mean operation time was 21 (range 15-35) min in the IMN group and 46 (range 40-110) min in the plate group. There was no statistically significant difference between groups according to DASH scores, Grace-Eversmann evaluations, grip strength, forearm pronation and supination degrees, type of fracture, length of hospital stay, and time between injury and surgery (p > 0.05). Complete elbow and wrist range of motion was achieved in all patients. CONCLUSIONS With similar union rates, functional results, and shorter operating times, locked IMNs are a suitable alternative to plate osteosynthesis in adult isolated diaphyseal radius fractures.