The electron paramagnetic resonance spectrum of a synthetic 0.15-carat diamond single crystal grown in a (Fe-Co-C) system using the temperature gradient method in a split-sphere type apparatus was studied. It was established that the electron paramagnetic resonance signal from P1 centers (representing N atoms occurring at the C sites) present in the diamond crystal upon a high-temperature high-pressure treatment exhibited inversion when the microwave power in the resonator was increased from 70μW to 70mW at a polarizing magnetic field scan rate from 0.5 to 5mT/min. No such inversion was observed in the initial diamond (before the high-temperature high-pressure treatment). Inversion of the EPR Signal from P1 Centers in a Synthetic Diamond Single Crystal Under Normal Conditions. N.A.Poklonski: Technical Physics Letters, 2006, 32[4], 309-11