Teratology Information Services (TIS) are started in different countries in Europe in order to gather available data on exogenous agents, to evaluate their pertinence to human subjects, and to apply this knowledge to specific cases. Most European centers can only be consulted by medical professionals. The experience of two such services (Lyon, France, and Bilthoven, The Netherlands) is described. Attention is given to the task of TIS, risk evaluation, operational methods, and functioning and future developments.