THE University hospitals of Son Dureta in Palma, Bellvitge in Hospitalet (Barcelona), Vall d'Hebron (Barcelona) and Salamanca are this year the big national reference centres offering the most complex specialities and have a great capacity for teaching and investigation. This was revealed by the Top 20 hospitals study, done each year by the company Iasist, which takes into account the quality, operation and the economic efficiency of Spanish health centres. The report was presented in Madrid by the director general of Iasist, Doctor Merce Casas, and the Consultant director of Iasist, Doctor Antoni Arias. It includes a ranking of Spanish centres with regard to heart disease. A total of 143 hospitals throughout Spain took part voluntarily in the report's evaluation, 116 public (some 52 percent of the total in the National Health System), and 27 private. Of these, according to Iasist, a total of 27 (23 from the National Health System and four private) stood out for their quality, operation and economic efficiency. In addition to this, the centres included in this list recorded some 15 percent fewer deaths and 11 percent fewer complications than the rest of the participants.