-- In order to improve children speech therapy, we develop a Fuzzy Expert System based on a speech therapy guide. This guide, write in natural language, was formalized using fuzzy logic paradigm. In this manner we obtain a knowledge base with over 150 rules and 19 linguistic variables. All these researches, including expert system validation, are part of TERAPERS project (financed by the National Agency for Scientific Research, Romania). I. INTRODUCTION The main objectives of speech therapy expert system develop by our team are [1]: - personalized therapy (the therapy must be in according with child's problems level, context and possibilities); - speech therapist assistant (the expert system offer some suggestion regarding what exercises are better for a specific moment and from a specific child); - (self) teaching (when system's conclusion is different that speech therapist's conclusion the last one must have the knowledge base change possibility).