Background. Liquid biopsies are powerful tools to non-invasively analyze lung cancer phenotype and progression as well as drug resistance. Polypeptide-GalNAc-transferases are emerging novel biomarkers related to cancer and GalNAc-T13 correlated with lung cancer behavior (1). The aim of this work was to evaluate GALNT13 expression (the gene coding for GalNAc-T13) as new potential liquid biopsy biomarker for NSCLC patients. Methods. GALNT13 expression in peripheral blood was detected using a nested RT-PCR (2). The specificity of the method was evaluated by analyzing 20 peripheral blood samples from healthy individuals; while sensitivity was evaluated using a dilution model with cell lines that simulate the clinical sample to be studied. Total RNA was extracted from circulating tumor cells (CTCs) from peripheral blood and plasmatic exosomes from patients with NSCLC, analyzing the expression of GALNT13 in duplicate. Results. No expression of GALNT13 was found in any of the samples from healthy individuals and the sensitivity of nested RT-PCR was established at 0.01%. GALNT13 expression was analyzed in CTCs from 34 NSCLC patients. GALNT13-positive CTCs were found in 22/34 (64.75%) lung cancer patients. This glycosyltransferase was detected in patients with different histologic type of NSCLC (Figure 1 A) as well as in different stage of disease (Figure 1 B). Finally, the preliminary results of GALNT13 expression in plasmatic exosomal RNA was concordant with those obtained for CTCs. Conclusion. In this preliminary study we demonstrate for the first time that GALNT13 expression in CTCs and plasmatic exosomes is a potential biomarker for diagnostic and monitoring of NSCLC patients.