The effect of substrate orientation on the quality of silicon epitaxial layers was studied in terms of deposition rate and surface topography. The layer was deposited by the hydrogen reduction of silicon tetrachloride. Deposition rate was determined from the time of deposition and from the layer thickness obtained by angle lapping and staining. Deposition rate was lowest on accurately oriented 〈111〉 substrates and increased as the degree of misorientation from the 〈111〉 direction increased. The frequently observed surface pyramid defect was found to be a function of (a) deposition rate and (b) substrate orientation. These pyramidal defects were not observed for low deposition rates, and when the substrate was misoriented from the 〈111〉 direction. These observations are consistent with the proposal that the deposition rate used in practice is determined by two fundamental rate processes, namely, (a) reaction rate and (b) growth rate.