CA 125 and CA 19-9 are antigenic determinants associated with human epithelial ovarian carcinomas. Murine monoclonal antibodies have been raised against these determinants, and immunoradiometric assays have been developed to monitor antigen levels in the serum of cancer patients. This study was undertaken to determine whether concomitant measurement of CA 125, CA 19-9, and carcinoembryonic antigen would provide a more precise correlation with tumor progression or regression than could be obtained with any single assay. Among 105 patients with surgically demonstrable epithelial ovarian carcinoma, serum CA 125 levels were elevated (greater than 35 U/ml) in 83%, CA 19-9, levels (greater than 37 U/ml) in 17%, and carcinoembryonic antigen levels (greater than or equal to 2.5 ng/ml) in 37%. Within individual samples, no correlation was found among values for the three markers, but patients with elevated CA 19-9 levels also had increased levels of CA 125. At least one of the three markers was elevated in 90% of the subjects. When 41 patients were monitored serially over 2 to 60 months, alterations in CA 125 levels correlated with disease progression or regression in 94% of instances, whereas alterations in CA 19-9 levels correlated in 33% and alterations in carcinoembryonic antigen levels in 25% of instances. Concomitant measurement of CA 125, CA 19-9, and carcinoembryonic antigen did not prove superior to measurement of CA 125 alone in the monitoring of patients with epithelial ovarian carcinoma.