Background. Ever since the first report of deltopectoral flap in pharyngo-esophageal reconstruction in 1965, various methods of flap reconstruction have been introduced, allowing surgical eradication of tumors that were once thought to be inoperable. Despite these advancement, many literatures emphasize distant metastasis and second primary malignancies as the most important factors that contribute to the low 5-year survival rate of the patients. Specific consensus about defining second primary cancer is still debatable, due to small number of reports regarding second primary tumors arising in flaps used for reconstruction of defects in the head and neck region. Case. We report a case of a 72-year-old male patient who, under the diagnosis of hypopharyngeal cancer, underwent total laryngectomy with partial pharyngectomy, extended right radical neck dissection with extended left lateral neck dissection, right hemithyroidectomy and radial forearm free flap reconstruction on June 16, 2003. After 37 cycles of radiation therapy, the patient exhibited no sign of recurrence. The patient revisited our department on June 14, 2016 with chief complaint of dysphagia that started two months before the visit. Radiologic studies and histology revealed squamous cell carcinoma in neopharynx, one that had been reconstructed with forearm free flap. Conclusion. Until now, only a handful of reports regarding patients with second primary cancer in reconstructed flaps have been described. Despite its rarity, diagnostic criteria for second primary cancer should always kept in consideration for patients with recurred tumor.