GaAs epitaxial growth by the open‐tube AsCl3&sngbnd;Ga&sngbnd;N2vapor‐transport technique was thoroughly examined as to its growth conditions, with some discussion on an optimum condition supplemented. The results of Hall, impurity profile, and photoluminescence studies for both the epitaxial layers grown in the nitrogen carrier gas and in the hydrogen carrier gas were described for the sake of comparison. A number of experiments successfully revealed a residual impurity in an undoped epitaxial layer. It was found that the present method exceeds the conventional one in many respects when preparing high‐purity uniform epitaxial layers.