The aim of this multidisciplinary project is to study the roughly one hundred ground-floor latrines in the city of Ostia, one of the main cities of the Roman Empire, port and image of Rome, as well as the fifty or so downpipes considered to be evacuations of upper storey latrines. Their study will allow us to understand, through archaeology, all aspects of their architecture. The archaeometric analysis of the samples taken from the stercoral concretions formed at the bottom of the pipes will provide a reliable picture of the sanitary state of the population, but also of its diet and environment. This project is in the continuity of the researches performed on the ancient latrines, which have been revived for the last 20 years. The paleoparasitological analyses, by revealing the presence of digestive parasites, will offer the possibility of discussing the effectiveness of the hygiene measures, implemented by such structures, on the parasitic infections circulating within the population. Palaeomicrobiological analyses will track bacterial and viral pathogens. The filling of latrines will allow the study of the spectra of animal and plant species consumed in different parts of the city as well as their natural environment. The project associates 7 partners with complementary and multidisciplinary skills under the direction of A. Bouet: Ecole française de Rome (E. Bukowiecki), Parco archeologico d'Ostia antica (C. Tempesta), Ausonius (A. Bouet), Laboratoire Chrono-environnement de Besançon (M. Le Bailly), PACEA (O. Dutour), ISYEB (T. Wirth) as well as CReAAH of Rennes (B. Ephrem). Palynology will be performed as service provided by the ARPA Laboratory (J. Argant). This innovative approach carried out on the whole of the Ostia latrines will be a first at the level of a Roman city of the imperial period in the western Mediterranean.