This article explores the subject of preliminary rulings in the Chilean Civil Procedure. Namely, it is focused on those issues which, due to their logical and legal connection to the object of the process, must be decided by the same or a different Court, before the final and substantial judgement is made. In order to provide a systemic development of the subject, only criteria accepted by the legal system will be used. Preliminary rulings can be either relative or absolute, depending on whether the power conferred to the judge is mandatory or discretionary. They can also be divided into devolutive and non devolutive, and into civil and criminal. Key words: Preliminary rulings, Jurisdiction, Res iudicata.