SUMMARY Background: The conventional cervico uterine cytology (CCUC) is the test of screening used in the precocious detection of the uterine cervix cancer, nevertheless its quality is discussed. Objectives: Evaluate the performance of the cytology in the screening of escamocelular invading cancer. Methods: 1980 users of Liga Santandereana de Lucha Contra el Cancer were selected. Following a prospective sampling, a statistical analysis was made to validate the cytology in the diagnosis to escamocelular invading carcinoma using like test of reference the histopathology information of biopsy. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was determined. Results: The cytology had a sensitivity of 12%, a specificity of 99%, a VPP of 83.3% and VPN of 98.2% in the identification to escamocelular invading carcinoma, in a population with a prevalence of the disease of 2%. Conclusions: In the present study the cytology had parameters of evaluation similar to the patterns internationally defined. Sensitivity as