The introduction of balloon valvuloplasty and new devices for coronary intervention has increased the incidence and changed the site and clinical presentation of cardiac perforation. We reviewed all cases of cardiac perforation that occurred during 11,845 consecutive catheterization procedures during a 6-yr period (1986-91). Fourteen cardiac perforations (overall incidence 0.12%) occurred as a result of the following procedures: mitral valvuloplasty 7 of 150 (4.7%), aortic valvuloplasty 4 of 260 (1.5%), pericardiocentesis 1 of 90 (1.1%), temporary pacer 1 of 1,660 (0.06%), and diagnostic left heart catheterization 1 of 6,965 (0.01%). Perforation was recognized in the catheterization laboratory in 11 patients, within 1 hr of leaving the laboratory in two patients, and 15 hr later in one patient. Hemodynamic evidence of tamponade developed in 13 patients and was confirmed by fluoroscopy (immobile heart borders) or echocardiography. Pericardiocentesis is definitive therapy in nearly half of the cases; the remaining patients require pericardiocentesis plus surgical repair of the perforation.