Not all possible side-effects of a pharmaceutical drug or medical device can be anticipated based merely on preapproval studies. The FDA Office of Surveillance and Epidemiology (OSE) within the Center for Drug Evaluation and Research (CDER) oversees a system of PMS programmes to identify adverse events that did not occur during the drug approval process. While not all parts of this surveillance system are new, navigating the surveillance landscape and its different components can pose some challenges. Sandra Blumenrath, DIA discusses.