Background: Humeral shaft fractures accounts 3% to 5% of all fractures with the incidence of 14.5 per 100,000 per year but debate still occurs as to whether these are best managed operatively or conservatively. The purpose of this study was to compare the outcome of humeral shaft fractures managed operatively versus conservatively and associated factors. Methods: Retrospective cohort study was conducted on patients treated at Tibebe Ghion specialized hospital starting from the beginning of February 2020 - February 2022 G.C that fulfill inclusion criteria and the data was collected from the charts. Frequency and percentage were used for variables to compare and summarize the results. The chi-square test was used to pick the association between the variables and relative risk was used to identify the strength of association between predictors/variables and outcome with confidence interval of 95%. P value < 0.05 was considered to be statistically significant. Result and discussion: Overall non-union was found in 27 (12.1%) of patients; 12.4% in operatively managed patients vs 11.7% in conservatively managed patients; however there is no relationship between the mode of management and non-union rate (X2 =0.025, df=1, p>0.05); But still some of studies showed low occurrence of non-union with in operative group and some with comparable results. Infection with RR=2.262(CI=1.076-4.755) which is also supported by previous studies, smoking with RR=3.352 (CI=1.402-8.015) and chronic disease like Diabetes mellitus, hypertension and HIV with RR=9.167(CI=6.284-13.372) are also found to be strong risk factors for non-union. Elbow stiffness was found in 93(41.7%) patients; with radial nerve injury being the strong risk for stiffness RR=2.077(CI=1.571-2.745). Patients who were treated conservatively had decreased risk of elbow stiffness with RR=0.686(CI=0.489-0.954); but pooled functional status/DASH score did not differ between conservative and operative treatment in previous studies. Conclusion: There is no association between mode of management and non-union; But conservative management has decreased risk of having elbow stiffness