As an increased environmental awareness has emerged among the world citizens, the WTO has begun to consider environmental issues to a further extent. The WTO mainly leaves environmental concerns outside its scope while MEAs have come to involve trade affecting measures. This work examines the relationship between the WTO and trade affecting measures contained in MEAs, including potential as well as factual conflicts of norms and jurisdictions. This work presents some core principles of the WTO, the definition of conflict, possible conflicts and common principles of international law on how the WTO agreements should be interpreted. Case-studies of CITES and the Kyoto Protocol are included as well as approaches on how to clarify this relationship and develop the dispute resolution of the WTO as well as MEAs. The concluding part examines possible solutions to these conflicts, discussing whether WTO violations may be justified either under article XX of the GATT, article XIV of the GATS or with reference to non-WTO law. This work should be especially useful to students and practitioners within the field of WTO law and international law in general.