Death occurring in some form of custodial detention is commonly known as death in custody, such as police cell or prison. A person in custody is entirely dependent on his custodians for his basic requirements hence this type of death raises questions regarding living conditions, inhumane treatment and violation of fundamental rights of prisoners. This prospective analytic study was carried out during period January 2019 to December2020 in Department of Forensic Medicine at PMCH Patna Bihar. This study observed 56 judical custodial deaths that maximum cases were males 93%and 7% were females. Age group above 55 years(40%). Maximum cases were brought in month of September(23%)followed by August (16%). Most prisoners died in hospital during treatment (82%).Deaths among 56 custodial deaths convict prisoners were dominated 41(73.21%) over undertrial prisoners 15 (26.79%) in jail custody.Pulmonary tuberculosis was the most common natural cause of death among prisoners. The natural causes was in 89% cases and unnatural in 11% cases . Majority of deaths in custody are due to natural causes and this may occur due to various factors like improper medical facilities, overcrowding in jail, old age, poor nutritional status, poor hygiene etc.