OBJECTIVE: A European concerted action (the EuroNatal study) investigated the background of differences in perinatal mortality between countries of Europe. The study aimed to determine the contribution of differences in quality of care, by looking at differences in the presence of suboptimal factors in individual cases of perinatal death. DESIGN: Retrospective audit study. SETTING: Regions of 10 European countries. POPULATION: 1619 cases of perinatal death. METHODS: Perinatal deaths between 1993 and 1998 in regions of 10 European countries were identified. Reviewed were singleton fetal deaths (28 or more weeks of gestational age), intrapartum deaths (28 or more weeks) and neonatal deaths (34 or more weeks). Deaths with (major) congenital anomalies were excluded. Cases were blinded for region and an international audit panel reviewed them using explicit audit criteria. MAIN OUTCOME MEASURES: Presence of suboptimal factors. RESULTS: The audit covered 1619 cases of perinatal death, representing 90% of eligible cases in the regions. Consensus was reached on 1543 (95%) cases. In 715 (46%) of these cases, suboptimal factors, which possibly or probably had contributed to the fatal outcome, were identified. The percentage of cases with such suboptimal care factors was significantly lower in the Finnish and Swedish regions compared with the remaining regions of Spain, the Netherlands, Scotland, Belgium, Denmark, Norway, Greece and England. Failure to detect severe IUGR (10% of all cases) and smoking in combination with severe IUGR and/or placental abruption (12%) was the most frequent suboptimal factor. There was a positive association between the proportion of cases with suboptimal factors and the overall perinatal mortality rate in the regions. CONCLUSIONS: The findings of this international audit suggest that differences exist between the regions of the 10 European countries in the quality of antenatal, intrapartum and neonatal care, and that these differences contribute to the explanation of differences in perinatal mortality between these countries. The background to these differences in quality of care needs further investigation.