Gastric carcinogenesis is a complex multistep process involving genetic dysregulation of proto-oncogenes and tumorsuppressor genes, and has recently entered the era of microRNAs (miRNAs), a class of small non-coding RNAs that posttranscriptionally regulate gene expression and control various cellular functions. MicroRNAs are small (approximately 22 nucleotides) non-coding RNAs that play fundamental roles in diverse biological and pathological processes, including cell proliferation, differentiation, apoptosis, and carcinogenesis. MicroRNAs have been revealed to be involved in various stages of cancer development, showing that abnormal miRNA expressions play critical roles in modulating expression of known oncogenes or tumor suppressor genes during cancer progression. Therefore, microRNAs can perform the function of onco-miRs or tumor-suppressor-miRs in gastric carcinogenesis. This review summarizes a current understanding of the connection between miRNAs and gastric cancer. Additionally, this paper outlines the applications of miRNAs in clinical practice, such as diagnosis, prognosis, detection, and therapy of gastric cancer.