Aneurysms occur in large arteries and are characterized by pathological widening of the vessel and thinning of the vessel wall. In the past decade, microRNAs (miRs) have emerged as key regulators of biological processes, and they were recently shown to be involved in aneurysm formation. A few miRs have been proposed to play a role in aneurysm development, such as miR-21, miR-26, and miR-143/145. Several recent studies describe the involvement of miR-29 in aneurysm formation by post-transcriptionally repressing the expression of extracellular matrix proteins. Therapeutic inhibition of miR-29 using anti-miRs attenuates experimental aneurysm formation in mice. This review provides an overview of the upstream regulation of miR-29 as well as the downstream targets of miR-29. It also discusses the potential clinical use for miR-29 inhibitors and the role of other miRs involved in aneurysm formation.