Background. The use of plasma as a "liquid biopsy" has gained increasing attention. The purpose of the present study was to evaluate the diagnostic and prognostic utility of the perioperative detection and quantitation of mRNAs encoding human telomerase reverse transcriptase (hTERT) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) in plasma from patients with cancer of the larynx or hypopharynx. Methods. We recruited 47 patients with laryngeal cancer and 2 patients with hypopharyngeal cancer, plus 27 healthy subjects. A blood sample was taken from each patient before and after surgical resection of the tumor. We quantified hTERT mRNA and GAPDH mRNA in plasma by real-time polymerase chain reaction (PCR). Results. Detection of hTERT mRNA before surgery had diagnostic value (sensitivity, 22%; specificity, 100%). Detection was more frequent in patients with supraglottic tumors than glottic tumors (p = .02) and was related to subsequent recurrence (p = .02). Preoperative levels of hTERT mRNA in plasma were higher in patients with subsequent recurrence (p = .046) and/or metastases (p = .047). The disease-free survival (DFS) and overall survival (OS) of patients with plasma samples positive for hTERT mRNA was poorer than that of patients with negative samples. Mean levels of plasma GAPDH mRNA in untreated patients were higher than in healthy subjects (p < .001). Conclusion. Detection and quantitation of hTERT and GAPDH mRNA in patients' plasma might be clinically significant in cases of laryngeal and hypopharyngeal cancer. (C) 2017 Wiley Periodicals, Inc.