The mathematical model of the process of rolling a continuous cast billet with defects of macrostructure on a smooth barrel and in calibers is presented. The boundary conditions are given by the speed of rotation of the rolls, the restriction of degrees of freedom of the workpiece and the rolls, as well as the coefficient of friction on the contact surface of the rolls-workpiece. For hot rolling, it was considered permissible to consider rolling rolls as a rigid, non-deformable rigid body. For the workpiece material used an elastic-plastic model of environmental behavior. There have been two cases considered: rollerless rolling on a smooth barrel and rolling in rectangular caliber. The roll material is steel, the surface is smooth. On the example of rolling in the first pass of the crimp mill, a comparative analysis of caliber rolling and rolling in calibers was carried out. It is shown that rolling on a smooth barrel has the potential to be used in the case of rolling continuous casting with macrostructure defects. The influence of the basic rolling parameters: absolute compression and temperature on the "healing" of macrostructure defects is made.