Tumor lysis syndrome (TLS) is an oncological emergency characterized by various metabolic abnormalities, such as hyperuricemia, hyperphosphatemia, hyperkalemia and hypocalcemia. Although TLS is rare in solid tumors, it has been reported in various cancers and sarcomas. It can be caused by chemotherapy, radiotherapy, surgical procedures. TLS in solid tumors may be lethal when it once develops. Hence, prophylaxis is considered important in medium risk diseases. We experienced the case that serum lactate dehydrogenase (LDH) level had elevated drastically a month prior to the onset of TLS in hypopharyngeal cancer. It is suggested that monitoring of LDH may be helpful for predicting the onset of TLS.