Background and Aim: Decision support systems(DSSs) refer to one of the types of information technology applications that can help clinicians to make right and timely decisions about patients. The aim of this study is to learn more about DSSs and their applications and effects on health care.

Materials and Methods: In this systematic review, articles which were published between 2000 and 2012, which were available as full texts through databases and search engines -- such as PubMED, EBSCO host research, Google scholar and Yahoo -- and which were also of clinical-trial type were examined; besides, certain books in this area were used as primary sources.

Conclusion : The findings show that DSSs were applied in five areas in health care, which had a significant effect on improving the process of care and the performance of providers. These areas are as follows: disease progress management(15.15%), care and treatment(27.27%), medication(27.27%), evaluation(27.27%), and preventation(12.12%). In general, improvement can be seen in three areas: quality of care and patient safety, cost effectiveness, and provider’s level of knowledge.