Abstract: OBJECTIVE To introduce the background of regulatory guidance, valuation and control strategy of genotoxic impurities in active pharmaceutical ingredient(API). METHODS Based on the understanding of regulatory expectations on the control of genotoxic impurity by studying of the history of European and US regulations, propose methods for assessing & controlling genotoxic impurities in drug substance. RESULT & CONCLUSION The most effective way to achieve the regulatory expectations is to establish control strategies based on a combination of semi-quantitative assessment, allied to analytical results and data from appropriate purging studies. Such an approach should ensure that any actual genotoxic impurity related risk is clearly identified and managed.