It is now well established that only clinical trials performed before drug approval are not sufficient for a full modern pharmacological evaluation of drugs and treatments. The need of both pharmacovigilance and pharmacoepidemiology is underlined in order to evaluate drugs under real conditions. After a summary of methods used in pharmacoepidemiological trials (spontaneous reports, imputability assessment, cohorts, case control studies etc.), recent pharmacoepidemiological data useful for the neurologist are summarized: side effects of tacrine and vaccines, serotoninergic syndrome and side effects of new antiepileptic drugs.