This thesis presents a model of expert system through the application of artificial intelligence techniques, which captures the basic knowledge that enables a person to act as an expert face complicated problems, in this case the expert system will take care diagnosed by Fuzzy Logic degree of malnutrition patient._x000D_ Expert System with the following characteristics is designed: the symptoms and signs of patients considered as input variables, one Base of Acts that stores individual patient's symptoms, a Knowledge Base represented by production rules formalized by predicate logic containing all the knowledge of human expert, an inference engine that uses tree search and / Or and finally the output variables._x000D_ Subsequently expert system simulation is performed by a prototype developed in the Eclipse IDE, likewise, is designed knowledge base with the help of the library "jFuzzyLog...