The most significant document written about Siam and the Ayuttaya era is Historia de las islas del archipiélago, y reinos de la gran China, Malaca, Siam, Camboya y Japón, publlshed in Barcelona in 1601 and written by fray Marcelo de Ribadeneyra. The history is composed of 6 books and describes the life, habits, believings and economy of various Asiatic countries, among them the Kingdom of Siam. The History is the account of the testimonies Ribadeneyra collected from Spanish missionaries that have exercised the apostolate in those countries, and that for one reason or another, ended up in Manila. At the end of the xxth century, it was translated from Spanish into English. Pacita Guevara Fernández made a comparative work with both texts. In this paper we are going to analyse its translation problems and strategies and we will propose preliminary solutions.