Carboxylesterases (CESs) play major roles in catalyzing the hydrolysis of a wide range of ester- and amide-containing compounds. CESs dominate both the biotransformation of numerous therapeutic drugs and the detoxification of environmental toxicants, and the activity alteration of CESs may be a determinant reason for modification of the resultant pharmacokinetic/pharmacodynamic profile when two or more drugs are concurrently used. Herein, we provide a comprehensive review of the current literature involving of induction and inhibition on CESs by both exogenous and endogenous compounds. In particular, the inhibition constant and inhibition pattern of inhibitors on CESs in studies using animal microsomes or human recombinant CESs are summarized. Further studies are needed to clarify the underlying regulation mechanism, and alterations in CESs activity should be taken into consideration for safe clinical therapy.