TATI marker (tumor-associated trypsin inhibitor) is most often assessed in patients with ovarian cancer. This paper presents the role and the usefulness of the marker in the evaluation of the treatment results in patients with endometrial cancer. The study was based on the evaluation of TATI marker level in 305 patients suffering from endometrial cancer treated at the Cancer Center between 1994 and1995 in Warsaw. In each patient the TATI marker level was measured from 3 to 7 times in the blood serum after each stage of the adjuvant treatment and in the initial part of the follow-up period. In order to assess the staging a postoperative protocol in force in 1988 (FIGO) was used and in accordance with this protocol, the patients were qualified for the adjuvant therapy, which consisted of the teletherapy, brachytherapy and hormonal therapy. All patients were observed on an outpatient basis after the treatment. The analysis of TATI marker levels in correlation with the features of cancer were carried out after a 17-year-long follow-up period. TATI marker levels have been evaluated in patients with unfavorable predictors identified in the operation protocol and in the histopathological protocol of the removed tumor. It was found that TATI level in the fourth sampling after the treatment was the most important value. TATI level increase in this assay was significantly correlated with the occurrence of local relapse or distant metastasis. The comparison of the results of patients with and without surgical removal of the lymph nodes has shown a significantly longer disease-free period in patients whose lymph nodes were not removed.