International comparisons of the perinatal mortality data derived from vital registration statistics can be made in different ways. In this article we examine the legal and administrative definitions of vital events (live births and stillbirths) in the 27 European countries that participated in an in-depth survey conducted in 1991 by the Institute of Demography, University of Louvain, Belgium. The impact of the various definitions in use on the comparability of vital event data over time and in different countries is illustrated by discussing some of the anomalies exhibited by published data (e.g., age at death in different European countries and the trends in infant mortality or stillbirth rate in selected countries). Analysed is the potential for vital registration systems to produce standardized perinatal mortality data that satisfy WHO recommendations for international comparisons, taking into account the contents of the vital registration forms and the data processing (record linkage) methods useful in different countries.