It is important to know the stresses and deformations of a rotating disk due to their practical application in all rotating machines, but also wherever there are high rotational speeds, such as brake discs, rims or hard drives. In recent times, with the development of materials and technology, the use of composite materials has become increasingly popular due to the possibility of "tailoring". Composites are anisotropic materials composed of two or more chemically and structurally different materials, combined at the macroscopic level for the purpose of obtaining a unique material with improved properties. Through this paper, the stress - strain relationship in a composite material based on the classical theory of lamination over stiffness matrices is presented. In the first chapter, the stress and displacement equations of a rotating disk are set. By “designing” the laminate to obtain a quasi-isotropic laminate, the effective values of the engineering constants were set, which can then be included in the expressions for the stresses and displacements of the disk. The mechanics of composite materials is analysed in the second chapter. The effective elastic constants of the composite material set based on the stiffness matrices, and the final expressions for the stresses and displacements of the rotating disk were solved using the MATLAB software package. Finally, the stress and displacement results of disks made of isotropic, and disk made of quasi-isotropic material based on the change in inner radius are compared.