Abstract： Objective To analyze and compare the clinical characteristics and the treatment outcome of the patients with chemo-resistant and relapsed gestational trophoblastic neoplasia (GTN).Methods The clinical records of the patients with refractory GTN treated at the Peking Union Medical College Hospital (PUMCH) from Jan 2005 to Dec 2007 were retrospectively reviewed.According to the reasons for referral, all cases were classified as chemo-resistant GTN group who had never a normal serum human chorionic gonadotropin-beta subunit (β-hCG) level during their previous treatment, relapsed GTN group who had elevated serum β-hCG levels in the absence of the pregnancy after finished treatment 3 months or more, and undetermined GTN group who had elevated serum β-hCG levels in the absence of the pregnancy less than 3 months after completed treatment.The clinical features and treatment outcomes were compared between undetermined GTN group and chemo-resistant GTN group and also between undetermined GTN group and relapsed GTN group, respectively.Results Of 81 patients with refractory GTN, 32 cases were defined as undetermined GTN, 38 cases as chemo-resistant GTN and 11 cases as relapsed GTN.The median number of previous chemotherapy regimens, the rate of serologic complete remission ( SCR), the patients who needed to change regimens due to resistance, and the patients who needed to change regimens in the undetermined GTN group and the chemo-resistant GTN group were 2.3 versus 3.1 ( P = 0.010),100% (32/32) versus 66% (25/38, P ＜ 0.01 ), 22% (7/32) versus 58% (22/38, P = 0.002) and 28% (9/32) versus 63% (24/38, P = 0.003 ), respectively.No significant difference were observed between undetermined GTN group and relapsed GTN group in clinical features, previous and current treatment or treatment outcome ( all P ＞0.05 ).Conclusions In order to evaluate accurately the treatment outcome of refractory GTN, it seems more appropriate for the patients who had reached the normal value of serum β-hCG when completed treatment to be defined as patients with relapsed GTN, while whose serum β-hCG levels elevated in the absence of the pregnancy after the completion of treatment, irrespectively of duration of stopping treatment.Comparing with the patients with chemo-resistant GTN, the outcome of patients with relapsed GTN is better.