Energy dispersion spectroscopy revealed the presence of copper oxides in the dimple structure of fracture of oxygen-containing copper (ETP grade). It was assumed that the oxide particles were surrounded by pores. Electron-ion microscopy with 3D imaging confirmed the presence of pores near the copper oxide particles in an oxygen-containing copper wire. The oxide particles represent inclusions with their longer axis orientated in the direction of preceding tensile deformation. The pore structure is extended in the same direction.