LncRNAs play critical roles in gastric cancer (GC). In this study, the expression of fourteen cancer related lncRNAs were investigated in paired tissues of 66 patients with GC, real-time RT-PCR revealed that ZFAS1 was significantly upregulated. We then examined the expression of ZFAS1 in plasmas derived from 77 GC patients before- and post-operations and 60 healthy individuals, and found that circulating ZFAS1 was also upregulated in GC patients and operation can reduce its presence in plasma. To investigate the potential mechanisms, we compared the expression of ZFAS1 in multiple gastric cell lines and one normal cell line and found that ZFAS1 was up-regulated in GC cell lines. Furthermore, circulating tumor cells (CTC) were simulated by mixing GC cells with peripheral blood. After EpCAM antibody-based cell sorting, we found that the expression of ZFAS1 was positively correlated with EMT property of CTCs. In GC patient tissue samples, we found that Twist was positively correlated with ZFAS1 by immunohistochemical staining. Taken together, our results suggested that ZFAS1 was up-regulated in both tissues and plasmas of GC patients, and may be involved in regulation of EMT in GC progression. Thus, ZFAS1 might serve as a potential diagnostic marker and/or therapeutic target for GC.