He is credited with translating a number of medical texts from Arabic, including works by Ibn Sina Avicenna, Abu-l-Salt, and Galen.

[1] Arnaldus' place and date of birth are debated: some historians believe he was born in Villeneuve-lès-Maguelone, a village near Montpellier; others are doubtful, because there are also towns of the same name in Aragon such as Villanueva de Jiloca, in the Kingdom of Valencia, in Catalonia, in Languedoc, or in the Provence.

He sought refuge from the Inquisition at the court of Frederick III in Sicily, and was later called to Avignon as a doctor for pope Clement V.[2] He is certainly behind the papal bull of 8 September 1309, which required of medical students knowledge of some fifteen Greco-Arabic treatises, including ones by Galen and Avicenna.

Many alchemical writings, including Rosarius Philosophorum, Novum Lumen, or Flos Florum, are also ascribed to him, but they are not authentic.

[3] He is also the reputed author of important medical works, such as Speculum medicinae and Regimen sanitatis ad regem Aragonum, but many others, such as Breviarium Practicae, were falsely attributed to him.

In addition, he wrote many theological works for the reformation of Christianity in Latin and in Catalan, some of them including apocalyptical prophecies.