Objective To explore the clinical value of serum CA125 in early ascites of primary hepatic carcinoma. Methods The serum CA125 levels in 111 patients with primary hepatic carcinoma and 23 health controls were determined. The CT scan and ultrasound examinations were used to detect the ascites in patients. The results were analyzed statistically. Results The CA125 level in primary hepatic carcinoma with ascites was obviously higher than that of non-ascites patients and controls (P<0.01). The serum CA 125 levels in stable non-ascites patients, developing of the patient and ascites patients were 29.56 U/mL, 168.35 U/mL and 187.00 U/mL respectively. The serum CA125 levels was correlated with degree of Child-Pugh (r=0.665, P<0.01). Conclusion The serum CA125 could be used to a useful method to diagnosis detection of primary hepatic carcinoma with ascites.