Objective: The early identification of gastric cancer (GC) represents a major clinical challenge. We conducted systematic review of studies evaluating the miRNA expression profiling as diagnostic tool in GC. Methods: We performed a search of PubMed, ISI Web of Science, and SCOPUS databases for studies on diagnostic miRNAs and GC, published in English up to October, 2017. Eligibility criteria included case-control studies evaluating blood or tissue-based miRNA expression profiles, and incorporating at least two detection phases (screening and validation). Results: We included 27 eligible studies, that reported on 97 deregulated miRNAs either in blood or tissue, out of which 30 were reported in at least two studies. Among 22 studies on tissue-diagnostic miRNAs, 13 consistently upregulated miRNAs (miR-214, miR-21, miR-103, miR-107, miR-196a, miR-196b, miR-7, miR-135b, miR-222, miR-23b, miR-25, miR-92, and miR-93), and six consistently downregulated miRNAs (miR-148a, miR-375, miR-133b, miR-30a, miR-193a, and miR-204) were reported. Ten miRNAs with inconsistent direction of expression in tissues were identified. Among the five studies performed on blood samples, only one miRNA was consistently upregulated (miR-20a). Conclusions: This review shows that some tissue or blood miRNAs may be considered as potential biomarkers for GC diagnosis, that urgently needs to be confirmed from large prospective studies. Clinical significance: Gastric cancer is commonly diagnosed as advanced-stage disease and the identification of biomarkers represents one of the major clinical challenges to date. Our study highlights the possible role of miRNAs in the diagnostic process of gastric cancer, representing a strong step forward and having practical implementation for future large-scale studies in the diagnostic field.