Background. The clinical value of pretreatment serum concentrations of cytokeratin 19 fragments, measured by Cyfra 21-1, was compared with tissue polypeptide antigen (TPA) and squamous cell carcinoma antigen (SCC-Ag) in 78 patients with squamous cell cervical cancer.Methods. Serum levels were compared with tumor stage, size, lymph node status, parametrial involvement, and prognostic data. The clinical performance of the different tests was evaluated by their receiver operating characteristic (ROC) curves.Results. Serum levels of all markers were related significantly to tumor stage and size. Elevated serum levels of these markers were not found to be predictive for the presence of lymph node metastases. In contrast, a positive relation was found between quantitative serum Cyfra 21-1, TPA, and SCC-Ag levels and the presence of either lymph node metastases or parametrial involvement (i.e., extracervical disease). An elevated, i.e. positive, serum Cyfra 21-1 level was related significantly to the presence of extracervical disease (P = 0.020). The clinical performance of each serum marker in predicting lymph node metastases or parametrial involvement appeared to be similar as expressed by their ROC curves. In the univariate analysis, Cyfra 21-1, TPA, and SCC-Ag showed prognostic value with respect to disease free interval and survival. Elevated serum levels were associated with a poor prognosis. However, after adjusting for tumor stage and size, none of these markers remained statistically significant.Conclusions. Cyfra 21-1 may be of additional value in assessing stage of disease, tumor size, and the presence of extracervical disease in patients with cervical cancer. Determining its value during follow-up warrants further study.