Background: Timely presentation and treatment with appropriately selected treatment option for radioulnar fractures significantly affect their outcomes. Delay in presentation and delay in time to treat these fractures, poor surgical techniques results in number of complications. Magnitude of complications and associated factors of radioulnar shaft fractures are not well studied in Africa. Study done in USA on Complications of plate fixation of forearm fractures by involving 87 diaphyseal forearm fractures (64 patients) which were treated by plating showed major complications occurred in 18 (28%) patients. Objective: Objective of this study is to assess magnitude of complications with radioulnar shaft fractures and associated factors among patients treated in Tibebe Ghion Specialized Referral Hospital Methods: Cross–sectional study was used to conduct this study. The sample size was calculated using Epi info 7.2.50 software versions with the population survey feature and with the assumption of 0.05 margin of error and 28% expected frequency. The sample size was 134 patients, from which 126 were included. Data was collected using data collecting format and transferred to SPSS version 23 for analysis. Frequency and cross tabulation was used to summarize descriptive statistics. Means and percentage were used for numerical variables. Graphs and tables are used for data presentation and dissemination. Cross tabulation and chi- square test were used for detecting the presence of associations between variables. P-Value <0.05 used to determine the association of variables and OR with 95% CI was used to determine the strength of association. Result: A total of 126 out of 134 patients (94.03%) were included: 102 males and 24 females with the Average age of 27.28 +/-8.940 years. The prevalence of complications after radioulnar shaft fractures was 35.7%. Results of Binary logistic regression showed that time of patient presentation after trauma (AOR = 12.295; 95% CI 3.691 – 40.963) and time to undergo surgery after their presentation to hospital was significantly associated with complications (AOR = 17.534; 95%CI 5.249 – 58.565). Conclusion: The overall prevalence of complications after radioulnar shaft fractures is higher than when compared to other studies. The independent risk factors for complications were presentation after 72 hours of trauma and undergoing definitive surgery after 24 hours of presentation.