Many developing countries are attempting to address the inequities of plant breeders' rights by incorporating farmers' rights provisions in their Plant Variety Protection legislations to reward the role of farmers' as conservers and enhancers of agro-biodiversity. Developing countries expect to generate substantial revenues for biodiversity conservation or for community reward schemes through the application of farmers' rights provisions. This paper applies a patent-renewal model to assess the economic returns appropriated by plant breeders from new (protected) varieties in developed countries. The estimates confirm a widely held view in the literature that plant variety protection is a relatively weak form of IPR protection which allows plant breeders to appropriate only limited returns from their innovations. Consequently, the application of farmers' rights provisions in a manner akin to breeders' rights is unlikely to be a source of significant revenue to developing countries.