Most research into psychopathy among prisoners is based on selected samples. It remains unclear whether prevalences are lower among European populations. This study aimed to measure the prevalence of psychopathy, and the distribution and correlates of psychopathic traits in a representative national sample of prisoners. Psychopathy was measured using the revised Psychopathy Checklist (PCL-R) in a second stage, cross-sectional survey of prisoners in England and Wales in 1997 (n = 496). Poisson regression analysis was carried out to examine independent associations between correlates and PCL-R total and factor scores. The prevalence of categorically diagnosed psychopathy at a cut off of 30 was 7.7% (95%CI 5.2-10.9) in men and 1.9% (95%CI 0.2-6.9) in women. Psychopathic traits were less prevalent among women. They were correlated with younger age, repeated imprisonment, detention in higher security, disciplinary infractions, antisocial, narcissistic, histrionic, and schizoid personality disorders, and substance misuse, but not neurotic disorders or schizophrenia. The study concluded that psychopathy and psychopathic traits are prevalent among male prisoners in England and Wales but lower than in most previous studies using selected samples. However, most correlates with psychopathic traits were similar to other studies. Psychopathy identifies the extreme of a spectrum of social and behavioral problems among prisoners.