To collect materials for the achievement of his great Chrysostom edition (Eton, 1610-1612), Sir Henry Savile twice commissioned his amanuensis James Dalrymple to the French Royal Library (Bibliotheca Regia) in Paris: in 1603 and again with Samuel Slade in 1606. The two scribes made use of various ancient Greek manuscripts from the collections of Fontainebleau and of Queen Catherine de' Medici. Later, in 1610, Slade transcribed as well several manuscripts at the Monastery of the Holy Trinity of Halki near Constantinople, some of which came in the 1730's to the Bibliotheca Regia, together with the manuscripts acquired by François Sevin in the Levant. Finally, Savile enjoyed the cooperation of the French Jesuit Fronto Ducaeus (1558-1624), which called upon his network of learned friends services for the edition and furnished collations of manuscripts. Can we identify the sources these researchers drew on and determine their importance in the Savile's preparatory work now kept at the Bodleian Library ?