Objectives.. A study through bibliometric indicators of the 1994-1999 Spanish international medical scietific output is presented. Method. The international bibliographic databases Science Citation Index and Social Sciences Citation Index were used as data source. Results. The Spanish production in Health Sciences rose in the period studied to 53,878 documents, distributed between Basic Medicine (54016), Clinical Medicine (53%) and Social Medicine (2.7%). Among the Spanish communities with greater production Madrid (31%) and Catalonia (29%) pointed out, followed by Andalusia (12%) and Valencia (9%). The principal institutional sectors involved in research were hospitals (51%) and university (44%). An important increase in the publications from foundations and companies was observed. The disciplines of Biochemistry/Molecular biology, Internal/General medicine and Pharmacology/Pharmacy pointed out by their high production. With regard to the centers of greater production its increase during the period studied, the clinical or basic character of research and the average impact factor of their documents shown to detect <<centers of excellence>>. Conclusions. The analysis carried out shows the growth of clinical and social Medicine, makes possible to identify the principal actors in Health Sciences, detect centers of excellence in the disciplines, and analyze the specialization of Spain in the European context. The publications are more abundant in the journals of the first quartile of each specialty.