The PCL-R is increasingly recognized as a valid and reliable method for assessing psychopathy in male forensic populations. However, most research has used North American samples. The present research gathered data from 73 percent of the inmates admitted to Grendon during 1995. The interviews took place soon after the inmates' arrival at the institution. Measures of internal consistency and inter-item reliability of the PCL-R were in the range of acceptable to good. Factor analysis using oblique rotation identified two main factors that were similar to the two-factor model proposed by Hare. Factor congruence coefficients indicated that the factors extracted were almost identical to those obtained in North American samples. Twenty-six percent of the sample were classified as psychopathy. This percentage was close to the levels reported in North American prison settings, but was considerably higher than that revealed in previous research involving samples in the United Kingdom. Findings were consistent with the selection criteria for Grendon; these criteria emphasize the presence of personality disorder or psychopathy as a prerequisite. Overall, findings offered further support to the growing literature attesting to the reliability and factor structure of the PCL-R. 40 references (Author abstract modified)