A combination of ultraviolet irradiation and egg rotation was applied to Korean frogs to study the mechanisms of the establishment of the dorsal-ventral polarity. Rotation of the uncleaved egg was capable of preventing the characteristic syndromes associated with UV irradiation. As well, brief rotation of the egg before cleavage relocates the site of dorsal lip to a novel location in the embryo at gastrula stage. That is, the dorsal lip appeared on the opposite side to gravity at the rotation of the egg. Above results were discussed with the informations obtained from other anuran and urodele species, and were interpreted in terms of regulating mechanisms for early embryogenesis.