Eighty percent of the patients with molar pregnancy go into spontaneous remission and do not require any therapy. Serial hCG determinations can identify the 20% who will develop malignant sequelae. It does not seem appropriate to treat all patients. This study was designed to assess several serum markers, including free β-hCG, total β-hCG, and CA-125 in order to identify persistent trophoblastic disease. The study was performed at Doctor Zekai Tahir Burak Women's Hospital, Department of Oncology. Forty-seven patients with complete hydatidiform mole were included in the study. In the spontaneous remission group (Group 1), total βhCG, CA-125 and freeβhCG values were 27988.7 ± 18491.6 mlU/ml, 51.7 ± 74.7 U/ml and 42.35 ± 28.4 mlU/ml, respectively. Patients in whom persistent trophoblastic disease had developed (Group II) the mean serum CA-125 and mean total βhCG values were lower than in group I, whereas the mean free βhCG value was higher but not significant. The mean value of free βhCG per total βhCG was found to be significantly higher in group 2. The free βhCG per total βhCG ratio seems to be a sensitive predictor of persistency of trophoblastic disease. Further prospective studies with a larger series of patients may warrant the exact predictive value of free βhCG per total hCG ratios.