This paper aims to evaluate the effects of additional tariff quotas on some Brazilian agricultural exports. The study focuses on the European offer in the negotiations for a Mercosur-European Union free trade agreement in May 2004. The economic analysis of the tariff quota shows that – given the demand curve – only one of the three components (the volume and the intra and extra tariffs rates) will effectively pose a restriction to the imports. So, the concession of an additional quota does not necessarily imply an equivalent increase in exports. In the es-timation of the gains, one must consider the change in the quota rent. Besides the administration of the quota systems will play crucial role on the allocation of the quota rent. If Mercosur gets in charge, the estimates indicate an addition of US$ 728 million in exports, of which US$ 525 million result from the appropriation of the quota rents and US$ 476 million from exports. The sum of both is indeed close to the value of the additional quotas at current prices. If the administration goes to the EU, the gains will derive exclusively from the expansion in exports, which corresponds to 63.7% to the value of the quota.