Objective: To describe demographic characteristics, morbidity and in-hospital mortality at the infectious diseases unit in a public reference teaching hospital in northern Lima-Peru. Material and Methods: A retrospective study was conducted including all admissions from January 1 st , 1990 to December 31, 2000, recorded in the discharge book of the Department of Infectious, Tropical and ... [Show full abstract] Dermatological Diseases of the Hospital Nacional Cayetano Heredia. Demographic characteristics, dates of admission and discharge, diagnoses, and discharge status were registered. Diagnoses were classified using the International Classification of Diseases, version 9 (ICD-9). Results: We recorded 7192 admissions, 4603 (64%) were male, the mean age was 39.2 ± 19.0 years. The number of admissions per year almost duplicated (from 440 to 817) during the study period. The mean age increased from 36.6± 16.1 to 41±19.9 years; admissions of elderly patients increased from 11.8% to 21.3%, and the HIV/non-VIH ratio increased from 0.07 to 0.25. The admission/bed ratio augmented from 12.2 to 22.7. The most frequent diagnoses were: HIV 1209 (10.2%), tuberculosis 1201 (10.1%), skin and soft tissue infections 653 (5.5%) and pneumonia 651 (5.5%). The overall in-hospital mortality was 8.1%, remaining constant throughout the study. Conclusions: There have been an increasing number of admissions in this setting, particularly of elder patients, without changes in overall mortality. Tuberculosis and HIV were the two most frequent diagnoses. (Rev Med Hered 2004;15:181-187).