The main objective of selecting this topic because of many pharmaceutical companies receives the 483 observations/ warning letters from the USFDA. The reason of most of 483 observations/warning letters was inadequate investigation of Laboratory Non-Conformances. It includes Out of specification/Out of trend investigation. The inadequate investigation because of unawareness of regulatory guidance requirements while performing the investigation. If any company receives 483 observations/warning letter it will impact on company reputation in the market and also impact on company revenue. So as to avoid this we should know the some basic concept while performing the out of specification/Out of trend investigation.