Eisai maintains medical research headquarters in Woodcliff Lake, New Jersey as well as locations in Japan, the United Kingdom, the Research Triangle in North Carolina, and Massachusetts where the Eisai Research Institute and the Andover Innovative Medicines Institute are based.
Eisai memiliki kantor pusat penelitian medis di Woodcliff Lake, New Jersey serta lokasi di Jepang, Inggris Raya, Research Triangle di North Carolina, dan Massachusetts di mana Eisai Research Institute dan Andover Innovative Medicines Institute berbasis.