The behavior of radiation-induced carbon-related defects in high-resistivity silicon detectors has been investigated. The defects were introduced by α-particle irradiation and investigated by deep-level transient spectroscopy. An unusual defect behavior consists in low-temperature annealing, including self-annealing at room temperature, of the interstitial carbon Ci with a simultaneous increase of the Ci-Oi-complex concentration. The kinetic parameters of the process have been determined from the increase of the Ci-center concentration versus time. Two annealing velocities have been observed, which arise from different heat treatments during the detector fabrication process.