Introduction: Fractures of the humeral shaft are commonly encountered in our hospital. Conservative management with hanging arm cast is preferred by some authors. Shoulder & elbow stiffness, non- union and mal-union are commonly seen with thistreatment. Open reduction and internal fixation with plate and screws require extensivesoft tissue stripping, radial nerve mobilization with high rates of radial nerve palsy. An interlocking intra medullary nail system has the advantage of stability and earlyfunctional recovery with fewer complications because of less soft tissue trauma andprovides stable fixation hence inter locking nail system has been used. Objectives:To document the clinical outcome and complications associated with the useof intramedullary interlocking nail in acute diaphyseal fractures of humerus in adultsin a consecutive series of patients at BIMS, Belagavi during the period of February 2022 to January 2023. Methods: 30 cases of acute humeral shaft fractures in adults more than 18 were treatedby closed reduction and internal fixation by Intra Medullary Interlocking Nailbetween February 2022 to January 2023 at our institution and followed for a minimumof 6 months. Outcome was assessed by using criterion done by ROMMEN et al. series. Results: All patients were followed up for an average of 3 to 4 months. Our series consisted of 30 patients, 19 male and 11 females. Mean radiological union in weeks was 13.6. There was one nonunion and one delayed union in our study. Conclusion: Based on our experience and results, antegrade technique is safe & reliabletechnique for treating acute humeral shaft fractures. The advantages of intramedullarynailing are minimal surgical exposure, better biological fixation, minimal disturbancesof soft tissues and early mobilization of neighboring joints Interlocking nailing alsoavoids complications like lack of rotational control, migration of nail and requirementof supplementary bracing.