Mindfulness Based Stress Reduction (MBSR) therapy is a meditation therapy, though originally designed for stress management, it is being used for treating a variety of illnesses such as depression, anxiety, chronic pain, cancer, diabetes mellitus, hypertension, skin and immune disorders.The aim of this systematic review is to determine the efficacy of MBSR in the treatment of chronic illnesses; it's mechanism of action and adverse effects. It describes an alternative method of treatment for physicians and patients that may help patients cope with their diseases in a more effective way.COCHRANE, EMBASE and MEDLINE were systematically searched for data on outcome of treatment with MBSR used alone or in conjunction with other treatments. The data available on prevention of diseases through MBSR was also analyzed.All the 18 studies included in this systematic review showed improvement in the condition of patients after MBSR therapy. These studies were focused on patients with chronic diseases like cancer, hypertension, diabetes, HIV/AIDS, chronic pain and skin disorders, before and after MBSR therapy.Although the research on MBSR is sparse, the results of these researches indicate that MBSR improves the condition of patients suffering from chronic illnesses and helps them cope with a wide variety of clinical problems.