Geminiviruses rely heavily on complicated protein-protein interactions between viral proteins and between virus and host plant proteins to establish successful infection. The bimolecular fluorescence complementation (BiFC) assay is based on the in vivo complementation of nonfluorescent component parts of a fluorescent protein through the interaction of proximity target proteins, each fused to a different part of the fluorescent protein. Here, we describe a protocol for the BiFC-based method for the identification of the interaction between geminivirus and plant proteins, which allows for the visualization of protein-protein interactions and the subcellular localization of protein interaction complexes in living systems.