For the first time ever the Belgian legislator has enacted detailed rules on unfair contract terms in B2B-contracts. The rules consist of a limited black list of clauses that are prohibited under all circumstances, a grey list of clauses that must be presumed unfair unless proven otherwise and a general clause prohibiting all terms creating a significant imbalance between the rights and obligations of the parties. Given their wide scope of application these rules might have a considerable impact on the freedom of will and legal certainty.