Measurements of electron paramagnetic resonance (EPR) at 9 and 35 GHz between 2 and 300 K in single crystals and powder samples of CuGeO3 are presented. Below 14 K a large decrease in the intensity of the Cu 2+ EPR signal is observed. The data can be interpreted as due to a spin-Peierls transition. However, an alternative interpretation in terms of a simple structural transition cannot be ruled out. An opening of an energy gap of ∼25 K is calculated from the analysis.