Plant Breeders Rights (PBRs) are sui generis IPRs intended to promote plant variety creation. Two characteristics distinguish PBRs from patents: the research and the farmers’ exemptions. This article attempts to assess the impact of these exemption rules on the private value of PBRs. For this purpose, a microeconometric model of PBRs renewals is developed and estimated. This model extends previous models of patents renewals by allowing the use of PBRs-specific variables. It is argued that simple tests on the coefficients associated to key PBRs-specific variables can provide insights into the impact of the two exemption rules. Implementation to PBRs in France over the period 1973-2011 for six major crops suggests that neither the farmers’ exemption nor the research exemption have a clear cut effect on the private value of PBRs. We conclude that there is no evidence to argue in favor of a reform of PBRs.