Background: There is a considerable lack of scientific estimate of psychiatric morbidity among Indian prisoners. Objective: The objective of the following study is to study the prevalence of psychiatric morbidity among prisoners. Settings and Design: A cross-sectional study at District Jail, Kozhikode, Kerala. Materials and Methods: A total of 255 prisoners who were inmates during the period from mid-April to mid-July 2011 participated in the study. The study subjects included both male and female remand or convict prisoners. Socio-demographic data, clinical history and criminological history were collected from each individual. Psychiatric morbidity was assessed using MINI-Plus. Statistical Analysis: Done by using SPSS version 16 (SPSS Inc, Chicago, USA). Results: A total of 175 subjects (68.6%) had a current mental illness. Substance use disorder was the most common diagnosis (47.1%). Antisocial personality disorder was diagnosed in 19.2%, adjustment disorder in 13.7%, mood disorder in 4.3% and psychosis in another 6.3% of prisoners. A high rate of a current psychiatric disorder was seen in male (69.7%) prisoners. A significant association was noticed for the different nature of crimes with psychiatric diagnoses and previous imprisonment. Nearly 4% of prisoners reported a moderate to high suicide risk. Conclusion: Mental health problems among prisoners were quite high. Mentally ill prisoners are at high risk for repeated incarceration. The increased rate of psychiatric disorders should be a concern for mental health professionals and the policy makers.