From 1851 onwards, every Belgian municipality was required to keep a register in which the presumed cause of death was recorded for each deceased person. This system was introduced following the cholera epidemics of the 1840s and provided, for the first time, a detailed picture of the population’s health. In cities, a physician usually determined the cause of death, but in many villages this task fell to family members or neighbours, resulting in a wide range of descriptions – often vague or imprecise – being added to the registers. Because there was initially no uniform list of diseases, many terms were difficult to compare. With the introduction of an official Belgian nomenclature in 1867 and the later adoption of the International Classification of Diseases (ICD) in the early 20th century, the quality of the registration improved significantly.

From the 1930s onwards, Belgium gradually shifted to confidential, anonymous cause-of-death forms: first in East Flanders (1930) and subsequently in all provinces by 1954. This transition marked the end of the traditional registers.

For privacy reasons, most of the historical causes-of-death registers were destroyed over time. However, a small number of municipalities have preserved (parts of) their series. The longest uninterrupted sequence is found in the city of Antwerp (1820–1946). The Antwerp data has been made accessible through the S.O.S. Antwerp database. In other municipalities as well, such as Châtelet (1867–…) and Zele (1852–1920), the surviving register data have been compiled into scientific databases.