In the course of the construction work and subsequent excavation in the historic part of Istanbul at Yenikapi in connection with the Marmaray Rail project linking the city's European and Asian parts with a tunnel under the Bosporus, numerous animal skeletons have been unearthed. This study is an overview of the preliminary examination results. Since project initiation in 2004 a great number of archaeological finds have been made, including animal remains scattered over the entire excavation area. Radiocarbon dating ( C) of the 54 animal species identified puts their age range from Early Byzantium (4t h -7t h century AD) to Late Byzantium (15th century AD). The most abundant skeletons were those of horses (Equus caballus L.).