The change in electromagnetic impedance of a conductor due to the presence of a long, perpendicular surface‐breaking crack in a normally incident, uniform electric field is calculated in closed form in the high‐frequency limit. At high frequencies, where the skin depth is much smaller than the depth of the crack, the fields near the edge and corners of the crack are effectively decoupled. This means that the solution may be formulated as the sum of contributions from the corners, faces, and edge of the crack. Simple analytical expressions for the electric field are found and used to calculate the impedance due to the crack in the high‐frequency limit without resorting to numerical methods.