Background : The present study attempted to detect a specific circular RNA (circRNA) for the early diagnosis of gastric cancer (GC). Methods: We selected four patients with GC for this study. The total RNA of the malignant and adjacent tissues was extracted, and the circRNA was screened. The eight most upregulated and downregulated circRNAs with a statistically significant relation to GC and paired adjacent nontumorous tissues were identified using real-time fluorescent quantitative polymerase chain reaction (PCR). CircRNA expression was identified by quantitative reverse transcriptase PCR in 78 cases of GC and adjacent tissues, and in the gastric fluids of 30 patients with chronic nonatrophic gastritis, 30 patients with chronic atrophic gastritis, 21 with early GC, and 57 with advanced GC. Results: A total of 445 circRNAs, including 69 upregulated and 376 downregulated circRNAs, showed significant aberrant expression in GC tissues. A majority of the differentially expressed circRNAs originated from chr1, chr3, chr4, chr6, and chr11. Hsa_circ_000780 was significantly downregulated in 80.77% of GC tissues, and its level in GC tissues correlated with the tumor size, tumor stage, T stage, venous invasion, carcinoembryonic antigen, and carbohydrate antigen 19-9 expression. A crucial observation was the presence of this circRNA in the gastric fluid of patients with early and advanced GC. Conclusions: The present study uncovered a new hsa_circRNA expression profile in human GC, of which hsa_circ_000780 was significantly downregulated in GC tissues and in gastric fluid. It can be potentially used as a novel biomarker for early GC screening.