Effects of thickness variation on natural frequencies of laminated conical shells have been studied by using a semi-analytical finite element method. Love's first approximation thin shell theory is used to solve the problem. Effects of various parameters, such as the number of layers of the shell, the semi-vertex angle, the slant length to small end radius ratio and the thickness variation parameter (maximum to minimum thickness ratio), are studied, particularly on the lowest natural frequency. Shells of linear symmetrically varying thickness, about the mid-length of the shell, have been considered for the analyis. During the computation, the mass of the shell was kept constant for a particular slant length to small end radius ratio in order to provide useful examples of the effect of the thickness distribution on the natural frequencies. © 1991.