A cross‐sectional transmisson electron microscope (XTEM) study of intrinsic solid‐phase epitaxial (SPE) growth in self‐ion‐implanted (001) Si has been carried out. The activation energy of the self‐ion‐implanted silicon was measured to be 2.6±0.2 eV. The value is remarkably close to those obtained in the two most recent studies by other techniques. The pre‐exponential factor is lower than that reported by Lietoilaetal. [J. Appl. Phys.53, 4399 (1982)] annealed under similar conditions. The variation in proximity to the surface and difference in the distribution of the microstructural defects in the two studies are suggested to be possible causes for the discrepancy. The advantages of utilizing the XTEM technique to study epitaxial growth of self‐ion‐implanted amorphous thin films are demonstrated. The accuracy in the XTEM measurement of the SPE regrowth rate in Si+‐implanted (001) Si is discussed.