Bare-metal stent is a vascular stent without a coating (as used in drug-eluting stents). It is a mesh-like tube of thin wire. The first stents licenced for use in cardiac arteries were bare metal - often 316L stainless steel. More recent ('2nd generation') stents use cobalt chromium alloy.
Drug-eluting stents are often preferred over bare-metal stents because the latter carry a higher risk of restenosis, the growth of tissue into the stent resulting in vessel narrowing. However, once tissue re-growth covers the metal stent in the vessel, there is a lower rate of blood clot formation (thrombosis) of the stent. As a result, patients with bare metal stents generally receive a shorter duration of blood-thinning anti-coagulation than do patients with drug-eluting stents, and bare-metals stents may be better for some patients for this reason.