Therapeutic drug monitoring (TDM) of psychotropic drugs is now a widely introduced practice, and it is especially recommended in patients who are non-compliant, or who poorly tolerate, or respond poorly to a medication, or who belong to the category of “special populations” (somatically ill patients, comedicated with a variety of drags, suffering from a liver or renal disease, elderly or very young patients). Increasingly, the use of generics has been shown to represent a source of unexpected treatment outcomes, and TDM may help to explain pharmacokinetic particularities after switching from an original to a generic preparation (or vice versa). Finally, the increasing knowledge of the metabolism of psychotropic drags allows to take account of the pharmacogenetic status (e.g. cytochrome P-450, P- glycoprotein) of the patients not only in adapting their medication, but also for interpreting pharmacokinetic interactions with clinical consequences. In this respect, TDM and pharmacogenetic tests (phenoty- ping, genotyping) have now also to be considered as a tool in pharma- covigilance. The aim of this course is first to briefly summarize some basic knowledge on TDM and pharmacogenetics of the metabolism of psychotropic drags. Psychiatrists who already have experience in this field will have their knowledge updated: recently progress will be illustrated by clinical situations, which will be discussed in an interactive way. A consensus paper (AGNP) with recommendations on the optimal use of TDM and pharmacogenetic tests in psychiatry will be summarized and submitted for discussion, by speakers (clinicians, clinical psychopharmacologists) from Switzerland, Sweden and Germany.