The measurement of the internal friction coefficient as a function of temperature has been used as a means of investigating defects created in artificial graphites by neutron irradiation at small doses (lower than 2 × 10 20 n/ cm 2) and at room temperature. Observations carried out on a compressed pyrographite, of properties very similar to those of the single crystal, show a behaviour ressembling that found in standard nuclear graphite, with differences inherent to the polycristalline nature of the latter material. The internal friction spectra plotted between − 180°C and + 500 °C at frequencies of about 1 Hz and relative strain amplitudes of the order of 10 −5 revealed, several distinct energy absorption phenomena —a continuous background which can be connected with the displacement of the dislocation bands, the level depending on the irradiation dose, —a dislocation-point defect interaction peak at around 0°C, also influenced by the irradiation dose, —a relaxation peak at about + 90 °C (frequency 1 Hz), appearing only for irradiation doses not greater than 10 20 n/cm 2 and apparently attributable to di-interstitial reorientations, —an internal friction maximum showing a direct connection with the restoration of the modulus after irradiation, which takes place between 200 and 500 °C and which we think can be ascribed to a reorganisation of irradiation-induced defects. On the basics of these results we have attempted to define the nature and developments of the defects after neutron irradiation. It seems that the presence of interstitial defects of the type suggested by Wallace affords an interpretation of most of the phenomena observed, but other possible explanations are considered.