Abstract: Objective To investigate the clinical value of 18F-deoxyglucose positron emission tomography／computer tomography （18F-FDG-PET） in diagnosis and treatment of choriocarcinoma. Methods The 18F-FDG-PET with simultaneously monitoring serum beta-human chorionic gonadotrophin （β-HCG） was carried out on 2 cases with choriocarcinoma. The increased metabolic abnormalities in metastatic lesions of lung， liver and pelvic were observed. Results In one patient， 18F-FDG-PET revealed the primary choriocarcinoma associated with pulmonary， liver and pelvis cavity metastases. The level of serum β-HCG decreased to normal level gradually and the SUVs of multiple lesions followed a normal distribution after EMACO chemotherapy. For another recurrence patient， serum β-HCG increased and pathology diagnosis revealed that few viable cells existed by undergoing radical hysterectomy， but 18F-FDG-PET detected no uptake. Conclusion 18F-FDG-PET is useful in diagnosis and treatment of choriocarcinoma by detecting the primary and metastasis sites， and possesses higher value in assessing cytoactive. Simultaneously monitoring serum β-HCG can decrease the false positive rate and false negative rate of 18F-FDG-PET.