Carbon–carbon (c/c) composites have low density, high stiffness and retain their properties at high temperature. The manufactured composite has significant internal damage like, voids, matrix cracking and debonding at interfaces due to the mismatch in thermal stresses induced during manufacturing process. Also there is some distortion of the cross-section of the fibre bundles. All these imperfections influence the mechanical properties of the composite. A computed tomography (CT) scan is performed on a composite specimen and 3D image is reconstructed. Unit cell is taken form the reconstructed image and is analyzed by using finite element (FE) method. The manufacturing imperfections are included in the FE mesh. Asymptotic homogenization along with periodic boundary conditions is used to determine the mechanical properties. Results obtained are compared to those available in the literature.