Fibrosis is a common pathological state characterized by the excessive accumulation of extracellular matrix components, but the pathogenesis of the disease is still not clear. Previous studies have shown that microRNA-29 (miR-29) can play pivotal roles in the regulation of a variety of organ fibrosis, including cardiac fibrosis, hepatic fibrosis, lung fibrosis, systemic sclerosis, and keloid. In this review, we outline the structure, expression, and regulation of miR-29 as well as its role in fibrotic diseases.