Prevalence rates of infectious diseases in post-trial prisons have been scarcely investigated. Due to the specific characteristics of these prison populations, these prevalence rates may differ from pre-trial prisons and more information is needed for developing adequate prevention and treatment interventions. This study compared prevalence rates of hepatitis B virus (HBV), hepatitis C virus (HCV), susceptibility to varicella zoster virus (VZV) and measles in pre- and post-trial detention.Data were collected in Geneva post-trial prisons among males (n=250), including serological tests, demographics, and risk factors, and were compared to those of the Geneva pre-trial prison (n=273).Incarcerated men in post-trial detention shared a disproportionate burden of infectious diseases compared to community (chronic HBV: 5.9%, HVC: 2.8%, susceptibility to VZV: 5.9%, to measles: 4.7%). Susceptibility to VZV and prevalence rate of HCV were lower in post-trial prisons (p=.034 and p=.080). Prevalence rates of infectious diseases in prison should be interpreted in light of the prison population's characteristics. Screening and treatment should be promoted in all types of prison settings. Since overcrowding and turnover of pre-trial prisons restrict the access to screening, prevention and treatment of infectious diseases, interventions are crucial in post-trial prisons.