This paper discusses the role of genetic factors as predictors of acute closure and restenosis after coronary angioplasty. Two examples are discussed: 1) The phospholipase A(2) (PlA(2)) polymorphism of the platelet glycoprotein IIIa gene, which is associated with different responses of platelets to various agonists, may be a genetic risk factor for coronary thrombosis after stent implantation. 2) The I/D polymorphism of the angiotensin-converting enzyme gene, which is associated with different plasma concentrations of the enzyme, may be a genetic risk factor for restenosis after coronary stenting.