The recent increase in reports of drug-facilitated crimes (sexual assault, robbery) has caused alarm in the general public. Drugs involved can be pharmaceuticals, such as benzodiazepines (flunitrazépam, lorazepam...), hypnotics (zopi- clone, Zolpidem), sedatives (for example neuroleptics) or anaesthetics (GHB, ketamine), drugs of abuse, such as cannabis, ecstasy or LSD, or more often ethanol. To perform successful toxicological examinations, the analyst must follow some important rules : 1. obtain as soon as possible the corresponding biological specimens (blood, urine and hair), 2. use sophisticated analytical techniques (LC/MS, HS/GC/MS, tandem mass spectrometry); and 3. take care on the interpretation of the findings. It is the intention of the authors to address a guideline to both medical and analytical personnel for toxicological investigations in case of drug-facilitated crimes.