Abstract In this contribution the interface between EC Public Procurement Law and Internal Market Law case law is analysed. The core question is to what extent primary Community law may be a source of obligations to tender as well as of justifications for not tendering. Some elements of the ''Transparency case law'' (Telaustria, Coname, Parking Brixen) developed in public procurement cases will be compared with other case law on the fundamental freedoms. This case law also raises new questions, for example the relationship with Article 86 and, in particular, the question whether the award of an exclusive right shall be subject to a transparent procedure. Attention is further given to possible justifications of a presumed infringement of transparency obligations, both under Article 86(2) EC and by virtue of ''rule of reason exceptions''. The ''interaction'' among possible derogations of transparency obligations, both under primary law and specific secondary law, completes the analysis. By way of general conclusion the authors find that the Transparency case law is in some respects open to criticism. However, this case law fits well into the wider body of case law relative to the fundamental freedoms of the Treaty. EC public procurement law genuinely is an integral part of the internal market law.