Abstract : We study in this work the influence of a thin obstacle on the behavior of incompressible flow. We extend the works made by Itimie, Lopes Filho, Nussenzveig Lopes and Kelliher where they consider that the obstacle shrink to a point. We begin by working in two-dimension, and thanks to complex analysis we treat the case of ideal and viscous flow around a curve. Next, we study three-dimensional viscous flow in the exterior of a surface. We finish by giving uniqueness of the vortex-wave system with a single point vortex introduced by Marchioro and Pulvirenti, in the case where the initial vorticity is constant near the point vortex.