Sexual sadism can be described as the sexual pleasure produced by acts of cruelty and bodily punishment. The most common method for evaluating sexual sadism is clinical evaluation, that is, evaluation based on the diagnostic criteria of nosological instruments such as the Diagnostic and Statistical Manual of Mental Disorders (DSM) or the International Classification of Diseases (ICD). It is also possible to evaluate sadistic sexual preferences by phallometry, which provides a physiological measure of sexual excitation by deviant and nondeviant scenarios. The most recently developed evaluation method is the Severe Sexual Sadism Scale (SESAS), a dimensional instrument that has been empirically validated. Despite the availability of all these measurement techniques, very little research has been conducted on their degree of convergence. Consequently, the aim of the current study was to assess the relationship between these three measures of sexual sadism. Our analyses were conducted on a sample of rapists (N = 72), assessed in a maximum-security penitentiary. There was no significant relation between phallometric scores and other measures of sexual sadism. There was, however, an important correlation between SESAS scores and Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) sexual sadism diagnosis. Our results are consistent with other phallometric studies, which reported no difference in the penile responses of individuals diagnosed as sadists and those not diagnosed as sadists. Results and implications for future research are discussed.