Four known cardiotonic steroids were isolated from roots of Adonis amurensis Regel et Radde and identified as digitoxigenin, cymarin, K-strophanthin and convallatoxin by chromatography on Amberlite XAD-2 resin and silica gel, high performance liquid chromatography and gel chromatography on Sephadex LH-20. In order to clarify the structure-activity relationship, thirteen related compounds of digitoxigenin were tested for the inhibitory activities for $Na^+,;K^+$-adenosine triphosphatase from guinea pig heart. The inhibitory activities of related compounds of digitoxigenin were dependent upon the dicarboxylic acid and amino acid components. The compound having both the arginine and suberic acid moiety showed the higher inhibitory activity. The sulfate and glucuronide of digitoxigenin exhibited much less potency than the parent genin.