Colposcopically directed punch biopsy and endocervical curettage is considered to be a "gold standard" in diagnosing premalignant lesions of the uterine cervix. However, in daily routine practice the CIN grade, assessed on the basis of colposcopically directed punch biopsy, sometimes differs from postoperative histopathological evaluation. Such a situation can influence the methods and outcomes of further treatment of women with premalignant lesions of the uterine cervix. OBJECTIVE The comparison of histopathological diagnoses of punch biopsies to postoperative findings. METHODS The accuracy of punch biopsies findings was evaluated in 104 women treated in the Gynecology Ward of the District Hospital in Kielce in the years 1996-2000. Women with cytological diagnosis of LGSIL and HGSIL were included to the study. Histopathological findings of colposcopically directed punch biopsies and endocervical curettage were compared to definitive diagnoses of postoperative material obtained by conization or hysterectomy. RESULTS Discrepancies between the diagnosis of CIN grade, evaluated by colposcopically directed punch biopsies, and postoperative findings were detected in 37 cases (35.5%). Lower grade of CIN evaluated in biopsy was found in 23 cases (22.1%). Discrepancies in this group were found most often when colposcopy was unable to examine the entire lesion and positive endocervical specimen was obtained by curettage. In 12 (11.5%) cases when preoperative diagnosis showed CIN an early invasion was detected in postoperative material. CONCLUSIONS Significant discrepancies were found between pre- and post-operative evaluation of CIN grade. Therefore in each case of LGSIL diagnosed in punch biopsy HGSIL should be ruled out. Expectant management of LGSIL lesions and ablative treatment of CIN should be performed only in centers with highly qualified medical staff experienced in colposcopy and cytology. It seems to be advisable to discriminate a group threatened with fast progression into CIN III or cancer among women with LGSIL (e.g. typing of high risk HPV, aneuploidy).