The Unified Patent Court is a court common to 18 EU Member States and offers a uniform and efficient system for patent litigation at European level. Creating such system requires clear and comprehensive procedural rules. Such rules are to be found foremost in the Agreement on a Unified Patent Court, the Statute of the Unified Patent Court, and the extensive Rules of Procedure. Understanding and navigating through the many rules is challenging, not least because the Court is in its infancy but also because national procedural laws played a key role in the process of creating a European system. This Article-by-Article Commentary explains the procedure of the Unified Patent Court against the framework of the provisions of the Agreement, drawing on the corresponding Rules of Procedure and Statute. In light of the role played by national laws, comparative insights indicate possible directions the UPC may take in future cases. Christoph Augenstein, Sabine Agé and Alex Wilson are highly experienced practitioners and litigators in patent law. The authors are experienced practitioners specialised in patent law.