Despite radical improvements in medicine over the past 60 years, patients maintain multiple health care pathways that include high utilization of unconventional treatments. The authors examine three possible relationships between mainstream and alternative medicine: opposition, integration, and pluralism. Opposition, the traditional ethical position that the medical profession must eradicate unconventional medicine for the good of the patient, has withered away. Integration of mainstream and alternative medicine is increasingly advocated in tandem with hospital-based programs that amalgamate the use of conventional and alternative therapies. While advocates of integrative medicine often speak of "evidence-based" complementary and alternative medicine (CAM), integration fosters double standards for validating conventional and unconventional treatments. Integration also ignores unbridgeable epistemological beliefs and practices between mainstream and alternative medicine. Pluralism, which has been relatively ignored, calls for cooperation between the different medical systems rather than their integration. By recognizing the value of freedom of choice in medical options, pluralism is compatible with the principle of patient autonomy. Nonetheless, the pluralistic model does not amount to a relativistic stance according in which there would be no objective standards for comparing the therapeutic merit of conventional and CAM treatments. As an ethical model, pluralism realizes that physicians must be prepared to disagree with patient choices to pursue alternative therapies, and urge patients not to forgo medically indicated treatment. Pluralism encourages cooperation, research, and open communication and respect between practitioners despite the possible existence of honest disagreement, and preserves the integrity of each of the treatment systems involved.