The quality of national perinatal mortality statistics was evaluated from a survey in nine maternity hospitals in Hainaut, Belgium (total births: 7862). The overall completeness of perinatal death registration was 86%. Under-registration was especially frequent in low birth weight babies. In 69% of cases, the birth weight value reported on death certificates was in exact agreement with the value in hospital records. Using detailed categories of causes, there was, in 37% of cases, agreement between the underlying cause on death certificates and the main cause identified in hospital records. Using gross categories of causes, the level of agreement was 56%. Disagreement was mostly due to the lack of specificity of the underlying cause on death certificates. The authors suggest ways to improve the quality of registration.