Polygraph testing is becoming increasingly important in sex offender treatment. Polygraph advocates cite dramatic increases in historical disclosures that presumably allow more precise targeting of treatment interventions, earlier detection of risky behaviors that often lead to new offenses, and improved treatment and supervision compliance. Based on this, they believe the procedure supports desirable behavior that continues to various degrees after treatment and supervision end. Opponents cite ethical problems related to inaccurate results, unproven accuracy rates, and risk that examinees may be coerced into making false admissions. To counter these criticisms, proponents have developed standards, best practices, examiner training and certification programs intended to reduce error rates and address ethical issues. Opponents argue that these measures have not been tested and that empirically established error rates and best practices may not be possible for a variety of reasons. This article reviews the current situation, leaving readers to decide the wisdom and ethics of using polygraph in their own practices.