Osteo-cutaneous flap are commonly used for reconstruction of bone defect after oncology surgery. The success of surgery depends on the viability of the bone flap. Bone scan is a known, but less performed method, to look for viability of bone flaps. We describe a case of 50-year-old lady, presenting with squamous cell carcinoma of left buccal mucosa (cT4N1M0) involving the skin and mandible. She underwent left segmental mandibulectomy and upper alveolectomy with neck dissection, followed by reconstruction using a fibular osteo-cutaneous flap and anterolateral thigh free flap. On postoperative day 10, the intraoral flap showed signs of nonviability. The patient was sent to nuclear medicine for assessment of viability of the free fibula flap. The patient underwent three phase 99mTc-methylene diphosphonate (MDP) bone scan and single-photon emission computerized tomography. Computerized tomography showing good tracer uptake in fibula confirming viability. The case reflects the use of 99mTc-MDP in viability assessment of the bone flap.