OBJECTIVE The objective of this study is to present dynamic changes within the population over 65 years of age who are covered by the Mexican Institute of Social Security (MISS), through morbidity and mortality analysis, during the last 6 and 10 years respectively. METHODS Based on data from the Epidemiologic Bulletins from 1990 to 1995 and from 1985 to 1994, the morbidity and mortality rates, respectively, were calculated for the Mexican population over 65 who are covered by the MISS. Incidence of diseases was used as a measure of occurrence and the ratio of morbidity and mortality rates was calculated as the measure of effect. RESULTS An epidemiological transition exists, with a tendency towards aging among this population. In terms of morbidity, infectious and chronic diseases coexist; as for mortality, chronic-degenerative diseases predominate. CONCLUSIONS This represents a challenge for health care within institutional services, as this population group begins to compete with other priority groups and emergency needs. Epidemiological surveillance and research is essential to support decision-making.