Let f, g : (C n , 0) → (C, 0) be reduced germs of holomorphic functions. We show that f and g have the same multiplicity at 0, if and only if, there exist reduced germs f and g analytically equivalent to f and g, respectively, such that f and g satisfy a Rouché type inequality with respect to a generic 'small' circle around 0. As an application, we give a reformulation of Zariski's multiplicity question and a partial positive answer to it. To cite this article: C. Eyral, E. Gasparim, C. R. Acad. Sci. Paris, Ser. I 344 (2007).