Syndromic surveillance is a monitoring methodology in which data from disease indicators are collected and interpreted as quickly as possible (in real time) to get an impression of the current morbidity in the population. In this case 'syndrome' means: behavior, signs and symptoms that may be indicative of an infection, without a proven pathogen, or incidents such as an environmental disaster. Syndromic surveillance has gained momentum in response to various international infectious disease threats, including the outbreak of severe acute respiratory syndrome (SARS) in 2003. In several European countries, syndromic surveillance has been used to monitor the impact of outbreaks or natural disasters and the health of visitors of mass events. Following the outbreak of an infectious disease, syndromic surveillance can be reassuring in the absence of an epidemic. Insight into burden of disease can provide guidance in adjusting care capacity to need. Several syndromic surveillance systems and pilot studies have been set up recently in the Netherlands. The costs, benefits and their best application should be evaluated in the near future.