The levels of CA125, CA19.9, CA15.3 CA72.4, and TATI were serially measured during and after chemotherapy in 43 patients with epithelial ovarian cancer having elevated concentrations of one or more of the antigens before initial surgery. The value of 35 U/ml was chosen as cutoff level of CA125 for the monitoring of disease. Changes in the serum levels of CA125, CA19.9, CA15.3, CA72.4, and TATI correlated with the clinical course of disease in 87.4% of 215, 76.3% of 80, 71.3% of 122, 76.0% of 167, and 48.5% of 101 instances, respectively. After the sixth course of monthly primary chemotherapy, elevated antigen levels were strong predictors of persistent disease, while normal antigen values were associated with both positive and negative second-look findings. It is worth noting that antigen levels above the cut-off limits before the third course, but still in the normal range after the sixth course, seemed to be predictive of positive second-look findings. Among patients with elevated antigen levels at diagnosis, clinical detection of neoplastic progression after treatment was stopped was preceded by an elevation of serum CA125 in 93.3% of 15 patients, of serum CA19.9 in 80.0% of 5 patients, of serum CA15.3 in 66.7% of 9 patients, of serum CA72.4 in 81.8% of 11 patients, and of serum TATI in 40% of 10 patients. In patients with positive CA125 assay at diagnosis, the concomitant evaluation of the other antigens did not seem to be of additional benefit for monitoring epithelial ovarian cancer. However, the measurement of the other tumor markers could represent an interesting biochemical tool for the management of patients with negative CA125 assay. In particular the evaluation of serum CA19.9 or CA72.4 could be very useful in the monitoring of patients with mucinous ovarian cancer, which often fails to express CA125 antigen.