The placebo effect has evolved from being thought of as a nuisance in clinical and pharmacological research to a biological phenomenon worthy of scientific investigation in its own right. It is now clear that the term placebo effect is too restrictive and, in fact, many placebo-related effects have recently been investigated. A placebo effect differs from a placebo-like effect in that the former follows the administration of a placebo, whereas in the latter no placebo is administered. However, in both cases, the psychosocial context around the treatment plays a key role. In recent years, placebo and placebo-related effects have been analyzed with sophisticated biological tools that have uncovered specific mechanisms at both the biochemical and cellular level. This recent research has revealed that these psychosocial-induced biochemical changes in a patient's brain and body in turn may affect the course of a disease and the response to a therapy.