Selective growth of GaAs using an Ar+laser beam is reported. The laser irradiation during growth in the substrate temperature range 400–525 °C forms a GaAs spot of 400 &mgr;m in diameter. The spot growth rate increases up to 1.3 &mgr;m/h with laser power and does not depend on the type of substrate conductivity. Temperature rise due to the irradiation is revealed to be 7° at 120 °C for the laser power of 500 mW (laser beam diameter 400 &mgr;m). A concentric circle pattern can be formed by diffracting a laser beam. These results strongly suggest that the growth rate enhancement arises from the photodissociation of metalorganic molecules.