The aim of the present review was to describe the mechanisms of several known miR, summarize recent studies on oncogenic miR (e.g. miR-21, miR-106a and miR-17), tumor suppressor miR (e.g. miR-101, miR-181, miR-449, miR-486, let-7a) and controversial roles of miR (e.g. miR-107, miR-126) for gastric cancer.