In this work we have introduced a new method for solving fuzzy differential equations .This method "based on the" fully fuzzy "neural network" to find "the numerical solution of" the "first order fuzzy differential equations" ."The fuzzy trial solution of" the "fuzzy initial value problem is written as a sum of two parts". The first part satisfies the fuzzy condition, it contains no fuzzy adjustable parameters. The second part involves fully fuzzy feed-forward neural networks containing fuzzy adjustable parameters. "Under some conditions the proposed method provides numerical solutions with high accuracy".