Si0.8Ge0.2/Si(0.8)Geo(0.2)O(2) interface defects were studied by the electron paramagnetic resonance (EPR) technique in 1 mu m thick epitaxial porous SiGe layers. Two different intrinsic interface defects, the silicon and germanium P-b centers, have been identified. These defects are respectively Si and Ge dangling bond centers with trigonal point symmetry. The EPR parameters such as g-values, linewidths and spin concentrations have been determined for different oxidation conditions : native oxide formation at room temperature and 300 degrees C low-pressure oxidation. The spin concentrations of the two defects strongly depend on the oxidation conditions. The spin concentration ratio differs from the [Si]/[Ge] atomic concentration ratio of the porous layer.