Applications of probiotics in the treatment of gastrointestinal disorders are gaining acceptance among patients, despite evidence that probiotics can present substantial health risks, particularly for patients who are immunocompromised or seriously ill. Patients will likely formulate their attitudes and beliefs about probiotic therapies with reference to interpretive frameworks that compare probiotics with more familiar therapeutic modalities, including complementary and alternative medicines, pharmacological therapies, and gene-transfer technologies. Each of these frameworks highlights a different set of benefit-to-risk considerations regarding probiotic usage and reinforces extreme characterizations of both the therapeutic promise and peril of probiotics. Considerable effort may be required to help patients make informed choices about probiotic therapies.