Beam induced lateral epitaxy (BILE) on truncated ridges was applied to the heteroepitaxial growth of GaAs on a Si substrate. A GaAs buffer layer was formed on the Si substrate, and then this GaAs/Si template was used as a substrate for the BILE process. As a result, overgrown regions of GaAs of widths as large as 6.5 μm were grown laterally from the sides of the truncated ridges. The growth regions had a flat, smooth top surface consisting of a (111) facet. Although stacking faults from the GaAs/Si template remained in the growth region, which are unfavorable for device applications, the lateral grown region has no dislocations. Thus, the BILE method is useful for reducing dislocations in heteroepitaxy.