The levels of serum soluble interleukin-2 receptor (sIL-2R) of 36 patients with ovarian cancer, 34 with benign gynecological tumors and 31 blood donors were measured by ELISA. Compared to those of benign and normal controls, serum levels of sIL-2R in patients with ovarian cancer elevated significantly (P < 0.01). Serum sIL-2R levels were likely related to types, clinical stage or histological grading of ovarian cancer. We were led to conclude that serum sIL-2R level may reflect the status of the immune system and the disease severity in patients with ovarian cancer. Its value as a marker for monitoring treatment and prognosis needs further studies.