Abstract Ergopinacone and 7-dehydrocholesterol-pinacone have been prepared by two different methods, viz., the boiling method and the carbon dioxide method. The products obtained by the two methods as well as diacetates and dibenzoates derived from them have been compared. It has been indicated that the two methods yield the same products. In conclusion the author wishes to express his hearty thanks to Prof. Y. Urushibara for his kind guidance and encouragement. He acknowledges also his indebtedness to Dr. K. Yamasaki for his advice and kindness in taking absorption spectra, and to Mr. Yasohachi Yamaguchi and to Ozi Seisi Co. for generous help.