National and international diffusion, composition of the collective of authors who publish in the journal, and cocitation were studies for the journal An. Med. Interna. Diffusion was analyzed by examining the presence of the journal in medical data bases and specialized libraries in Spain. The institutional affiliations and geographical location of authors were determined on the basis of the affiliations given in the article by-lines. The journal is included in the major medical data bases and in approximately 80% of the libraries studied. The predominant professional affiliation among authors was clinical (hospital); the geographical origin of the authors (expressed as a percentage of all authors) approximately paralleled the volume of scientific publications generated by each of Spain's 17 autonomous regions. The cocitation study showed that An. Med. Interna ranked somewhere in the middle of the group' of 38 Spanish medical journals considered representative of research being done in Spain.