Electronic Journal of Differential Equations, Vol. 2005(2005), No. 105, pp. 1-11. Title: Fixed point theorem and its application to perturbed integral equations in modular function spaces Authors: Ahmed Hajji (Mohammed V. Univ., Rabat, Morocco) Elaidi Hanebaly (Mohammed V. Univ., Rabat, Morocco) Abstract: In this paper, we present a modular version of Krasnoselskii's fixed point theorem. Then this result is applied to the existence of solutions to perturbed integral equations in modular function spaces. Submitted October 14, 2004. Published October 3, 2005. Math Subject Classifications: 46A80, 47H10, 45G10. Key Words: Modular space; fixed point; integral equation.