Thick shells made of composite materials have been analyzed by using a higher order shell theory. In this theory thickness normal strain and two transverse strains are included. A higher order three-noded isoparametric axisymmetric finite element is used to solve the problem. Numerical experiments with the present element indicate that this element yields accurate vibration results with very few elements. In the present study, the suitability of different theories used for vibration studies has been investigated. Three theories are compared, viz. Love's first approximation shell theory, an improved theory with shear deformation and rotatory inertia, and a shell theory with thickness normal strain and shear deformations. It is found that the shear deformations have an appreciable effect on the vibration characteristics of comparatively thick shells, especially composite shells. A parametric study has been conducted to study the effects of various geometric properties of shell on the free vibration characteristics of conical isotropic and composite shells. The effect of mass distribution on the natural frequencies is also studied in the present work. © 1992.