SiC crystals grown in the cavity of a Lely furnace have been studied experimentally at 2500°C. In this study, special attention was called to the initial stage of recrystallization.The results obtained are summarized as follows;1) At the initial stage of recrystallization, β-SiC often crystallizes out. These crystals of β-SiC disappear with the progress of the subsequent recrystallization.2) Two dimensional growth layers having no growth spiral are often observed on the basal surfaces of the initial platelets. Most of these crystals show one-dimensional disorder.3) The transition from β- to α-SiC at about 2500°C seems to occur mainly through a vapour phase.4) When the growth cavity is poorly supersaturated, β-SiC fails to appear. In this case, however, α-SiC initially formed often shows one dimensional disorder.5) From these experimental results, it is concluded that the thermal stability gap between SiC polytypes has a certain relation to the kind of polytype to occur.