Developing countries required under the WTO TRIPs agreement to provide some intellectual property protection for plants are choosing Plant Breeders' Rights (PBR). TRIPs specifies only an effective sui generis system without further clarification. This article develops an effective system based on the detailed TRIPs patent requirements. In general, the requirements map well with current UPOV Acts. A complete analysis must also consider implementation. The US registration system, which allows limited distinctness, provides weaker protection than European examination systems. Some evidence indicates the US system provides inadequate protection while European systems may release too few varieties. The recent UPOV initial variety system should use high initial variety standards to discourage breeders from delaying introductions. UPOV 1991 makes seed saving a national option; preliminary results indicate seed saving does not unduly reduce breeders' profits, but may lead to growers unprofitably delaying replacing seed.