Introduction: The Magnitude of delayed long bone fracture fixation was variable in deferent setups; it reached 67.7% to 81 %. The reasons mentioned were shortage of operating theater slot, increased age, sever associated injury, and comorbidities. In our setup, both the magnitude and associated factors for long bone fracture definitive fixation with intramedullary Nail were not studied. Objective: To assess magnitude and associated factors of delayed long bone fracture fixation with Intramedullary Nail in Tibebe Gion specialized hospital from January 13/2019-January 16/ 2021GC. .Method: The study was conducted using a cross –sectional study and 290 patients were selected from patients admitted and operated at Tibebe Gion specialized hospital using SIGN nail from January1/2019GC to January 13/2021GC and registered on SIGN online database. The Data was collected from SIGN Online Surgical Database and patient’s chart and entered into Epi-Info version 7.2 and analyzed with the Statistical Package for Social Science (SPSS) version 26. To describe the study population, descriptive statistics were used. Binary logistic regression was used to assess the influence of independent factors on the dependent variable. The final association was presented using Adjusted Odds ratio (AOR) with 95 % confidence interval (CI) and P value < 0.05 level of significance as cut of point. Results: The magnitude of delayed long bone fracture fixation was 64.1% (95% CI: 59-69.7). The mentioned reasons for were lack of operating time ( 52%), medical conditions/comorbid (16.7%), sever associated injury(9.8%) , lack of SIGN nail implant (2%), lack of blood (1.5%), lack of Fund (1%) and others(17.2%) like, contaminated open fracture , delayed antibiotics initiation etc. Time from injury to debridement [AOR: 7.934, 95% CI (1.314, 47.898)], Severity of open fracture (GustiloAnderson open fracture classification) [AOR: 2.891, 95% CI (1.037, 8.060)], were significantly associated with Delayed long bone fracture definitive fixation with SIGN nail. Conclusion and Recommendation: The magnitude of delayed long bone fracture definitive fixation in Tibebe Gion Specialized Hospital was high. Time from injury to debridement and irrigation, severity of injury (GA classification), and sever associated injury were factors significantly associated with delayed long bone fracture definitive fixations. Therefore, intervention should ensure for patients with open long bone fracture to have early debridement and irrigation and definitive fixation. Key words; delayed fixation, long bone fracture, SIGN, Reasons for delayed long bone fixation