We aimed to evaluate critically the evidence behind the perceived inverse association between the degree of psychopathy as reflected by a high score on the Hare Psychopathy Checklist-Revised (PCL-R) and treatment response. A literature search with the key identifiers of PCL-R (or its derivatives) and treatment response produced 24 studies that were then systematically evaluated. This showed that only three studies were of an appropriate research design to answer the question and of these, none met our standard for an acceptable study. We conclude therefore that the commonly held belief of an inverse relationship between high-scores on the PCL-R and treatment response has not been established.