The subcellular localization of plant farnesyl diphosphate synthase (FPPS) was examined. Immunocytochemical staining using anti-FPPS1 antibody followed by electron microscopy showed that FPPS1 was localized to chloroplasts of rice mesophyll cells. Subcellular fractions from wheat leaves were examined by immunoblot analysis. FPPS was detected in the chloroplast fraction in wheat, and was protected from proteolysis following trypsin treatment of chloroplasts. FPPS was also detected in the chloroplast fraction of a dicot plant, tobacco.