Objectives : This study was intended to compare genetic differences and anti-oxidative effects of Achyranthis Japonicae Radix, Achyranthis Bidentatae Radix and Cyathulae Radix. Methods : The genetic differences of Achyranthis Japonicae Radix, Achyranthis Bidentatae Radix and Cyathulae Radix were observed with RAPD analysis. Anti-oxidative effects of Japonicae Radix, Achyranthis Bidentatae Radix and Cyathulae Radix were investigated. Result : 1. As the result of RAPD analysis, Achyranthis Japonicae Radix was found to be genetically similar with Achyranthis Bidentatae Radix. 2. There was a little difference in the DPPH free radical scavenging activity, lipid peroxidation inhibiting activity, SOD activity of Achyranthis Japonicae Radix, Achyranthis Bidentatae Radix and Cyathulae Radix. Generally, Achyranthis Japonicae Radix was found to have stronger effect than the others. Conclusions : Achyranthis Japonicae Radix and Achyranthis Bidentatae Radix were genetically similar. Achyranthis Japonicae Radix, Achyranthis Bidentatae Radix and Cyathulae Radix all exhibited anti-oxidative action.