Pharmacovigilance can be defined as a set of practices aiming at the detection, understanding and assessment of risks related to the use of drugs in a population, and the prevention of consequential adverse effects. In a narrower sense, the term refers exclusively to postmarket surveillance. This paper briefly outlines how pharmacovigilance has come to play a central role in the regulation of novel pharmaceuticals. However, the focus of the text is on mechanisms emerging in an experimental drug scene that aim at dealing with the risks posed by 'designer drugs' newly introduced to the black market. This discussion of pharmacovigilance and 'post-black market surveillance' is situated in the broader context of the more recent dissemination of vigilance as a key element of government in a world too complex for legal and disciplinary measures alone.