Foreign prisoners have a high vulnerability in terms of morbidity and access to care in overcrowded Italian prisons. This paper presents and comments on the management model of infectious diseases in foreign prisoners at our outpatient clinic, in order to describe a model of management for these conditions. Overall, 133 subjects (mean age 35.5 years) from 29 countries were followed for a period of 15 years. The most commonly represented area of origin (54.1%) was the Maghreb region. HCV infection (40.6%), HIV (22.5%), HBV (9.8%) and co-infection (15%, HIV/HCV or HIV/HBV) were observed. Ten subjects had tuberculosis, and only 30% of them were compliant with the treatment. Only 46.3% of HCV mono-infected patients completed the entire diagnostic process and even a lower percentage (37%) of them took treatment regularly. 90% of HBV mono-infected patients and 84% of those HIV mono- and co-infected completed the diagnostic workout. 77% of patients in each group took therapy regularly. Overall, the results show limited effectiveness. Therefore, it would be necessary to improve communication between healthcare professionals and correctional systems. Moreover, it appears urgent to reduce overcrowding in prisons to limit morbidity in prisoners.