According to the principle of procedural autonomy Member States of the EU are free to determine their own national procedural rules in the context of the application of consumer protection law. However, national procedural rules must meet the principles of equivalence and effectiveness. These principles imply 1) that national rules of procedural nature must be applied without distinction, whether the infringement alleged is of European Union law or national law and 2) that national procedural rules may not make it impossible or extremely difficult for consumers to exercise their rights conferred by EU law. Both principles, as well as the interpretation of certain open norms, have played an essential role in the case law of the European Court of Justice relating to consumer protection law and have led to a containment of the procedural autonomy. The objective of this research is to find out 1) to what extent Member States of the EU are still free to determine national procedural rules in the context of consumer protection legislation, 2)to what extent the case law of the ECJ derogates from traditional principles of Belgian procedural law and 3) to what extent the requirements set by the case law of the European Court of Justice are actually applied by the Belgian courts. Wheras the first two question are especially of a theoretical nature, the third ons is empirical and requires an in depth analyses of Belgian court decisions relating to consumer law.