We have carried out in situ observation of homoepitaxial growth on Si(1 1 1) 7 x 7, whose structure is known as the dimer-adatom-stacking-fault (DAS) model, by scanning tunnelling microscopy at 356degreesC. In order to grow epitaxially, it is necessary to cancel the underlying DAS structure. At low Si coverage, we observed small clusters within half unit cells. Then, large clusters that have no atomic image are formed. After further Si deposition, these large clusters change into a two-dimensional (2D) island with atomic protrusions, which implies that the underlying reconstructed layer was cancelled. After that, the 2D island transforms into the DAS structure. (C) 2002 Elsevier Science B.V. All rights reserved.