The observance of treatment boundaries maintains the integrity of the therapist-patient relationship. It is the therapist's professional duty to establish appropriate treatment boundaries. Basic boundary guidelines are reviewed. The principles underlying these boundary guidelines are explored. A clinical vignette describing the sexual exploitation of a patient by her therapist dramatically illustrates progressive boundary violations. Boundary violations involving money are particularly common. Double agent roles also are likely to lead to the establishment of dissonant treatment boundaries with patients. The clinical, ethical, and legal issues surrounding the maintenance of treatment boundaries are discussed.