ABSTRACT
Microbiological data deviations ( MDD) investigation differs from out of the standard ( OOS) investigation in chemical inspection items. Investigating Out-of-Specification( OOS) Test Results for Pharmaceutical Production issued by FDA specifically ex-cludes microbiological and other biological assays. Until recently, there is not a definitive guideline for MDD investigation in the world. Some institutions and experts have explored the practice and theory of MDD investigation. Referred to the existing practical experience and theoretical achievement and based on the provisions of Chinese GMP (2010 revision) and the requirements of Chinese Pharmaco-poeia Ⅱ(2010 edition) Appendix XIX Q, the article discussed the methods for MDD laboratory investigation.