FIFTY-FIVE THOUSAND RAPES ARE REPORTED YEARLY IN THE UNITED STATES; AN ESTIMATED 2.2 RAPES ARE COMMITTED FOR EACH 1 REPORTED. WHEN INCARCERATION DOES FOLLOW CONVICTION, THE RECIDIVISM RATE REMAINS QUITE HIGH (I.E., 22 TO 36 PERCENT 5 YEARS AFTER RELEASE). RAPES ARE COMMITTED BY A HETEROGENOUS GROUP OF OFFENDERS. SOME ARE THE RESULT OF SOCIOCULTURAL INFLUENCES, OTHERS ARE DUE TO SPECIFIC PSYCHOLOGICAL CONFLICTS. PHYSIOLOGIC MEANS HAVE BEEN USED TO EVALUATE THE EROTIC PREFERENCES OF RAPISTS. RAPISTS AND NONRAPISTS APPEAR TO SHOW SIMILAR ERECTION RESPONSES TO EXPLICIT DESCRIPTIONS OF MUTUALLY ENJOYABLE, CONSENTING INTERCOURSE, HOWEVER, THEY DIFFER IN THEIR ERECTIONS TO DESCRIPTIONS OF RAPE SCENES. ALSO, THERE IS A STRONG CORRELATION BETWEEN RAPE INDICES AND THE RAPIST'S LIKELIHOOD OF HAVING INJURED HIS VICTIMS DURING THE ACT OF RAPE. PHYSIOLOGICAL MEASURES CAN ACCURATELY IDENTIFY THE SADIST OR SADISTIC RAPIST AND PINPOINT THOSE RAPISTS LIKELY TO SELECT THE MORE VULNERABLE VICTIM, THE VERY OLD OR VERY YOUNG. THESE PHYSIOLOGIC MEASUREMENTS ARE CAPABLE OF PROVIDING PREVIOUSLY UNKNOWN AND SIGNIFICANT INFORMATION REGARDING THE RAPIST'S CHARACTERISTICS. SOME SUCCESSFUL TREATMENT METHODS INCLUDE DECREASING EXCESSIVE AROUSAL TO RAPE OR MOLESTING CHILDREN; INCREASING AROUSAL TO APPROPRIATE PARTNERS; AND DEVELOPING HETEROSOCIAL, ASSERTIVE, OR EMPATHETIC SKILLS. WHAT IS NEEDED IS THE TREATMENT VEHICLE FOR APPLYING THESE TECHNIQUES TO BOTH INCARCERATED AND NONINCARCERATED AGGRESSIVES. (LWM)