Despite declarations about health and social inequalities by the World Health Organization (WHO) and the Italian Constitution, the Italian penitentiary health system often does not meet the needs of the prisoners. This article summarizes the findings concerning contextual and structural reasons for these deficiencies (in part as reported by a prisoner rights association) and describes an Italian Ministry of Justice project to promote health by creating homogeneous groups of comorbidity for epidemiological study. Data and analysis on certain pathologies in the prison population are presented with special regard to addictions, hepatitis C virus, and cardiovascular problems. One etiological hypothesis focuses on the factors of promiscuity, excessive smoking, sedentary life, and stress. The conclusion is that prisoner health is a problem not only of inmates but for society.