Human ovarian tumor-associated antigen (TAA) has been purified from ovarian tumor tissue by affinity chromatography on concanavallin A-Sepharose and three different gamma globulin-Sepharose columns. The resulting ovarian TAA appears to be contaminated by one normal antigen or family of antigens. Rabbit antiserum prepared against this purified ovarian TAA (antiserum 404) was coupled to CNBr-activated Sepharose 4B. This coupled Sepharose was added to fractionated serum from ovarian cancer patients with Stage III and IV malignancy. Bound protein was eluted with 0.2M glycine buffer and tested against antiserum 404. The bound protein contained TAA identical to the TAA isolated from ovarian tumor tissue.