The sensitivities of the in–plane macroscopic linear stiffnesses of perfectly elliptical–cell honeycombs to geometric imperfections are derived through an analytical method and a finite–element–based numerical solution. The sensitivities of the honeycomb stiffness to three types of initial imperfections are studied. These imperfections are the deviation from circularity of a cell, a uniform change in thickness of honeycomb cell walls and thickness variations along the honeycomb cell wall. The sensitivities of the in–plane macroscopic stiffnesses to the deviation from circularity of the cell and to the thickness change of the honeycomb cells are derived analytically. The sensitivities of the in–plane properties to thickness variations along the cell wall are obtained numerically.