Gastric cancer (GC) is still a major aggressive malignancy worldwide. While the importance of circular RNAs (circRNAs) involved in carcinogenesis has gradually been acknowledged, their role in human cancers is not largely understood, including in GC. Here, we focused on hsa_circ_0001368 in GC, a novel circRNA that has not been previously reported. In the current study, we found a broad downregulation of hsa_circ_0001368 in GC tissues and cells, which correlates with a worse prognosis in GC patients. Functional experiments suggested that the knockdown of hsa_circ_0001368 promoted cell viability and motility by cell proliferation and invasion assays. In addition, the knockdown of hsa_circ_0001368 led to accelerated tumor growth in vivo. Mechanically, we demonstrated that hsa_circ_0001368 served as a competing endogenous RNA (ceRNA) to sponge miR-6506-5p. Subsequently, FOXO3 may act as the functional target of miR-6506-5p, and the knockdown of hsa_circ_0001368 decreased the expression of the tumor-suppressive gene FOXO3. Taken together, our study revealed that hsa_circ_0001368 plays a tumor-suppression role in GC via the miR-6506-5p/FOXO3 axis and may serve as a potential target for GC therapy. (C) 2019 Elsevier Inc. All rights reserved.