The analysis of historical death certificates has enormous potential for understanding how the health of populations was shaped by diseases and epidemics and by the implementation of specific interventions. In Brazil, the systematic archiving of mortality records was initiated only in 1944 – hence the analysis of death registers prior to this time requires searching for these documents in public archives, notaries, parishes and especially ancient cemeteries, which are often the only remaining source of information about these deaths. This article describes an effort to locate original death certificates in Brazil and document their organization, accessibility and preservation. To this end, we conducted an exploratory study in 19 of the 27 Brazilian states, focusing on the period surrounding the 1918 influenza pandemic (1913 to 1921). We included 55 cemeteries, 22 civil archives, and 1 military archive. Apart from few exceptions, the results show the absence of a curatorial policy for the organization, access or even physical preservation of this material, frequently leading to unavailability, deterioration and ultimately its complete loss. This study indicates the need to promote the preservation of a historical heritage that is key to understanding historical epidemiological patterns and human responses to global health threats.