Meditation, as a psychological intervention, has become of increasing interest to psychologists who conduct clinical research with or provide clinical services to medical populations. Mindfulness-based stress reduction (MBSR) is a manualized program which teaches a variety of meditation techniques and has frequently been used in medical settings with mixed medical populations. The following is a review of the literature, which provides preliminary support for the effectiveness of MBSR in specific medical populations, including persons with chronic pain, cancer and heart disease. Despite these encouraging findings, experts agree that continued research is needed, especially controlled studies with more rigorous methodology.