This is a comparative commentary on Council Directive 96/61/Ec of 24 September 1996 concerning integrated pollution prevention and control (IPPC), which is to be implemented in EU member states before 31 October 1999. The provisions of the IPPC Directive contain a number of uncertainties and ambiguities which were discussed, but not fully resolved, during the negotiation process. In particular, some provisions raise questions of interpretation which will confront national courts when interpreting and applying the implementing legislation in the light of the Directive. The authors aim to contribute to this discussion by analyzing key provisions of the Directive in the context of national approaches and experiences and of an economic appraisal of the Directive. The issues discussed include the notions of best available techniques and best practicable environmental option, the issuance of single integrated licences as opposed to the coordinated issuance of several permits for one facility, and the relationship between the IPPC process with environmental impact assessment and planning law regimes.