We investigated the usefulness of tumor-associated antigen (TA-4) by a radioimmunoasay method in estimating the extent of disease and tracking the clinical course of disease in 58 patients with cervical cancer. According to our results and those of other authors, the normal range of serum TA-4 was arbitrarily taken to be less than 2 ng/ml. The proportion of the pretreatment positive serum TA-4 level of 48 squamous cell carcinoma patients was 60%. And 40% in 5 adenocarcinoma patients. Advanced disease group showed higher incidence of positive serum TA-4 level; 40%, 72%, 63%, and 100% in stage I to IV, respectively. And the absolute values of TA-4 were higher in advanced disease. In patients treated with radiation, elevated serum TA-4 level usually declined after 3000 cGy and further dropped to normal range in 44c13 after 5000 cGy. The Positive rate in Primary cervical cancer was 59% (32/54) and 100% (4/4) in recurrent cervical cancer. And 15 patients with recurrent or persistent disease during follow-up revealed 80% positive serum TA-4 level. In conclusion, it would be suggested that serial serum TA-4 measurements may be helpful in tracking the clinical course during and after treatment.