Some experiments were carried out in order to obtain further informations in connection with the production of iron single crystals by the recrystallization method. Round bars, 3∼5 min in diameter, prepared from five materials containing 0.06∼0.13 percent carbon (commercial pure iron and soft steels) were heated up to 1000° in a moist hydrogen stream and then for different time-intervals at that temperature. It was found that a greater part of carbon had already been removed during heating up, indicating that the diffusion of carbon in α-iron is faster than in γ-iron. The degree of grain growth during heating up to 1000° is however, much smaller than that during heating at that temperature. The decarburization velocity is shown to be inversely proportional to the diameter of specimen.Specimens containing 0.06∼0.015 percent carbon and 40∼90 grains per square millimeter, prepared by the decarburization treatment at 1000° for two days, were elongated to various degrees and then annealed at 880°C for two or three days. The maximum grain growth was obtained with specimens elongated to about 4 percent. The grain growth was found to be independent of the heating velocity in the recrystallization heat-treatment. Especially for specimens of 4 mm diameter, the grain growth was completed by heating at 880° for two days. It is noteworthy that, for the materials examined, the higher is, the purity the more pronounced the grain growth, though it is known that in the especially pure material the grain growth is rather less marked.