Abstract: Fuzzy systems are extensively used in both applied and experimental medicine and are one of the most prevalent subjects of today’s Medical Informatics. Despite some limitations of their use due to information, economical, educational and other reasons these systems are widely acknowledged in medical institutions operating in all levels of healthcare. The accuracy of some up-to-date fuzzy systems today matches the diagnostic abilities of physicians that are why it holds an important role in risk-assessment and diagnostics in pharmocology. In this paper, I have done work on the fever symptoms that help in the diagnosis of dengue fever symptoms with the help of some doctors on the basis of fuzzy rule system I tried to give a better identification of dengue fever on the sample based, on the lab features and clinical symptoms.