['Previous studies have established that soluble interleukin-2 receptor alpha (sIL-2R alpha) levels are elevated in ascites and sera from individuals with advanced ovarian cancer (International Federation of Gynecology and Obstetrics [FIGO] Stage III/IV). This study was undertaken to evaluate sIL-2R alpha levels in individuals with benign ovarian neoplasms and early stage ovarian cancer (FIGO Stage I/II). Comparison with CA 125 levels was performed to assess screening potential.', 'Sera from 92 healthy individuals, 61 with benign adnexal masses, 12 patients with FIGO Stage I/II ovarian cancers, and 27 patients with FIGO Stage III/IV ovarian cancers were assayed for sIL-2R alpha by enzyme-linked immunosorbent assay and CA 125 by radioimmunoassay.', 'The mean serum sIL-2R alpha levels for benign pelvic masses, and Stage I/II and Stage III/IV epithelial ovarian cancer were 1507 +/- 82, 1631 +/- 274, and 2596 +/- 384 U/ml, respectively. The difference between mean serum sIL-2R alpha levels in individuals with benign adnexal masses and Stage III/IV epithelial ovarian cancer was statistically significant (P < 0.05). In addition, of the four individuals with FIGO Stage I/II ovarian cancer who had CA125 levels below 35 U/ml, the accepted upper limit of normal, three patients had elevated serum sIL-2R alpha levels. Eleven of 12 patients (92%) with potentially curable Stage I/II disease had elevated serum levels of either sIL-2R alpha or CA125 and 8 of 12 (67%) had elevations of both sIL-2R alpha and CA125. Sensitivity and specificity of a combination of CA 125 and soluble IL-2R alpha were 88.5% and 27.1%, respectively.'] Is soluble interleukin-2 receptor alpha elevated in sera of patients with benign ovarian neoplasms and epithelial ovarian cancer?