The free vibration characteristics of orthotropic circular cylindrical shells are analysed using Love's first approximation shell theory. Semianalytical finite element method is used as the method of solution. Shells of clamped-clamped and simply supported-simply supported boundary conditions are analysed with thickness varying along the axial direction. The influence of thickness distribution on natural frequencies, especially on lowest natural frequency, is studied. The effect of degree of orthotropy on natural frequencies of shells is also investigated. © 1990.