It is doubtful that any feature of the American health care system in the last several decades has had as profound an effect on the way Americans pursue their perceived health needs as complementary and alternative medicine (CAM). Almost half of all Americans take care of some of their health care needs outside of contemporary scientific medicine. The number of visits to CAM practitioners was estimated 6 years ago to be 629 million a year, with expenditures of $27 billion a year. The use of CAM has been expanding rapidly despite little objective evidence of its safety or effectiveness. Little more than a decade ago CAM was viewed by the traditional medical community as a nuisance that offered unproven treatments at best and as outright quackery at worst. In any case, alternative medicine, as it was known at that time, seemed unworthy of serious attention.