Medical articles with porous polymeric structures and methods of forming thereof are disclosed. The porous structure can have pores sizes that are nanoporous or greater than nanoporous. The porous structure can be a coating or layer of a medical device such as a stent, stent graft, catheter, or lead for pacemakers or implantable cardioverter defibrillators. Additionally, the body of the medical device can be a porous polymeric structure. The porous structure can be made from bioabsorbable polymers. The porous structures can be formed by contacting a polymer with a supercritical fluid.