〔Abstract〕 To investigate the expression and biological function of circular RNA (circRNA) hsa_circ_ 0002938 in gastric cancer. Methods 45 pairs of tumor tissues and para-cancerous tissues from gastric cancer pa- tients who underwent tumor reduction surgery at the hospital were collected . Human gastric cancer cells SGC-7901 , BGC-823 , HGC-27 , MGC-803 and immortalized gastric mucosal epithelial cells GES-1 were routinely cultured . RT-qPCR was utilized to detect the expression of hsa_circ_0002938 in gastric cancer tissues and cells . Chi-square test was used to analyze its association with the clinicopathological characteristics of patients , and the Kaplan-Meier method was employed to assess the relationship between hsa_circ_0002938 expression levels and patient prognosis . The effects of hsa_circ_0002938 on the proliferation , migration and invasion abilities of gastric cancer cells were detected by CCK-8 , scratch wound healing and Transwell assays . Bioinformatics was used to predict the miRNA and its downstream target genes that hsa_circ_0002938 might bind to . The competitive endogenous RNA regulatory network was constructed and the functions of the target genes were enriched . Results The expression of hsa_circ_ 0002938 in gastric cancer tissues and cells was much higher than that in para-cancerous tissues and GES-1 cells (P < 0. 05) . By contrast , patients in the high hsa_circ_0002938 expression group had significantly shorter 2-year pro- gression-free survival than that in the low expression group after surgery (P < 0. 01) . Moreover , knocking down the expression of hsa_circ_0002938 reduced the proliferative , migratory , and invasive abilities of gastric cancer cells (P < 0. 05) . Bioinformatics predictive analysis showed that hsa_circ_0002938 could bind to hsa-miR-342-3p and hsa-miR-503-5p . The downstream target genes of miRNA were involved in several cancer-related pathways , like mitogen-activated protein kinase (MAPK) , hippo and Wnt signaling pathway . Conclusion Hsa_circ_0002938 , which is highly expressed in gastric cancer tissues and cells , is closely associated with poor patient prognosis . Knockdown of hsa_circ_0002938 inhibits the proliferation , migration , and invasion abilities of gastric cancer cells . The study reveals the potential role of hsa_circ_0002938 in the progression of gastric cancer , offering new insights into its prevention and treatment.