OBJECTIVE To assess the availability, success rate and complications of microvascular iliac crest free flap for reconstruction of mandibular segmental defects. METHODS In this retrospective-descriptive study, we report patients who had undergone segmental mandibular resection for pathologic lesions and received reconstruction with iliac crest microvascular free flap between 2016 and 2019. Clinical and demographic data of all the cases were collected. Success was regarded as complete consolidation of the bone graft in panoramic radiograph. Postoperative complications were defined as major or minor based on the need for intervention. T-test, Kolomogorov_Smirnov, and multivariate analysis were used and the p-value<0.05 was considered to be statistically significant. RESULTS Of all 30 patients, 16 were women and 14 were men with an average age of 27.2 years (range 14-40). Patients were followed for 12-60 month (mean: 38.4). One flap was lost due to unsalvageable venous thrombosis. Six other cases had post-op complications while smoking and diabetes were associated with more complications (P = 0.036). Twenty-three patients received primary reconstruction which was more successful than secondary ones (P = 0.003). Osteogenic sarcoma was associated with greater risk of complications (P < 0.01). CONCLUSIONS The results of this study suggest that iliac crest microvascular free flap serves as a promising option for the reconstruction of mandibular defects, providing excellent contour and acceptable success rate with low donor site morbidity. Future studies will focus on the role of systemic diseases in post-op complications and flap failures.