The present study was undertaken to establish the diagnostic utility of total sialic acid (SA) determination in the serum of patient with ovarian neoplasia. In a group of 29 patients with histopathologically confirmed ovarian neoplasia, concentrations of total SA was determined. In addition, the two tumor markers: CA125 antigen level and lactic dehydrogenase (LDH) activity were determined. The mean value of serum total SA in patients (1.76 mmol/L) was significantly higher than in the control group of healthy women (1.52 mmol/L). The elevation of serum total SA was associated with the burden of the tumor: higher total SA levels were observed in the cases of more developed malignancies. A significant correlation has been found between serum total SA content and CA125 level in patients with undifferentiated ovarian cancers. It has been concluded that total serum sialic acid level reflects the development of malignancy and should be considered as a supporting tumor marker in ovarian cancer diagnosis.