The aims of this study were to determine the incidence of coronary artery perforation by intracoronary guide wires during angioplasty, to identify associated factors, and to assess outcomes. The retrospective analysis covered 4,353 consecutive procedures, corresponding to a total 6,994 lesions treated over a period of 8 years. Coronary artery perforation by guide wires occurred in 15 cases (0.35%). Perforation was associated with the number of hydrophilic wires used (odds ratio=2.33; 95% confidence interval, 1.34-4.05) and treatment of chronic occlusions (odds ratio=3.31; 95% confidence interval, 1.05-10.46). Cardiac tamponade occurred in seven cases (46.7%), six of which were subacute. Three cases were resolved by pericardiocentesis, while four required surgical drainage. Cardiac tamponade was associated with the number of guide wires used (P=.039) and the use of abciximab (P=.016). No death occurred.