The results of the Registry of the Working Group on Cardiac Catheterization and Interventional Cardiology of the Spanish Society of Cardiology for 2003 are presented. Data were obtained from 112 centers representing nearly all cardiac catheterization laboratories in Spain; 104 centers performed mainly adult catheterization and 8 carried out pediatric procedures only. In 2003, 105,939 diagnostic catheterization procedures were performed, including 90 939 coronary angiograms, representing a total increase of 8.5% in comparison to 2002. The population-adjusted rate was 2171 coronary angiograms per 106 inhabitants. Coronary interventions increased by 14.4% in comparison to 2002, with a total of 40,584 procedures and a rate of coronary interventions of 969 per 106 inhabitants. Coronary stents were used in 92.5% of the procedures (47,249 units implanted, for a total increase of 22% in comparison to 2002). About one fifth (20.2%) of the implanted stents were drug-eluting stents (11,699 units). A total of 6080 percutaneous coronary interventions were done in patients with acute myocardial infarction, representing an increase of 27.5% in comparison to 2002, and accounting for 14.9% of all interventional procedures. Of the noncoronary interventions recorded, we note the increase in percutaneous mitral valvuloplasties (21.6%) and atrial septal defect closures (86%), and also the increase in pediatric interventions (13.3%). In conclusion, we emphasize the high rate of reporting by laboratories, which allows the Registry to compile data that are highly representative of the activity at cardiac catheterization laboratories in Spain.