The aim of our study was to quantify the hospital demand originating from prisons and describe the main diagnoses as a measure of prevalence, as well as communicable diseases and their evolution during the period 2000-09. Using the discharge records of the University General Hospital under the terms of an agreement that meets the demand for hospitals from prisons in the province of Valencia, we carried out a cross-sectional study of the frequency distribution of diagnoses and their distribution according to personal characteristics. More than 2,415 discharges were recovered, which, after the removal of inconsistencies, provided 2,332 episodes of hospitalization. The average age of the subject ranged from 32.8 to 39.5 years. The most common grouped primary and secondary diagnoses (table 2) were: 1. HIV (34.05%), 2. Hepatitis C (14.67%), 3 º. Drug dependence (10.25%), 4 º. Pneumonia (8.58%), 5. TBC (7.46%). In the last decade there has been a change in the patterns of infection in the prison population. This may be related to: the relative aging of the prison population, the replacement of intravenous use by other non-invasive means, the change of nationality of prisoners and therapeutic advances in the treatment of HIV infection.