The objective of this paper is to compare histologic results of microbiopsies and/or endocervical curettage obtained following the older cytological "atypical" diagnosis and the newer Bethesda ASCUS terminology. We reviewed a series of atypical smears (n = 245) from December 1991 to February 1995 and ASCUS cases (n = 120) from March 1995 to May 1996, when some atypias were renamed ASCUS according to the Bethesda classification. These patients were examined by colposcopy for cervical lesion and clinical evaluation. Menopausal women were underrepresented in atypical smears (n = 21/245, 8.6%) in comparison with ASCUS (n = 29/120, 24.2%, P = 0.001). Since, no low or high grade squamous intraepithelial lesion (L/HSIL) was ever found in the >/= 50 years group, we reviewed only patients under 50 years. Atypical smears resulted in 61/224 (27.2%) positive biopsies of which 47 (21%) were LSIL and 14 (6.2%) were HSIL; ASCUS smears yielded 17/91 (18.7%) positive pathology diagnoses with 13 (14.3%) LSIL and 4 (4.4%) HSIL. Endocervical curettage positivity (ECC) was at 6/109 (5.5%) for atypias, and 1/53 (1.9%) for ASCUS. Cervical biopsies in ASCUS smears show a tendency to a lower histologic positivity rate, in comparison with atypical cytology. Persistent ASCUS smears should be evaluated by colposcopy, and thereafter at 6-month intervals. The exact meaning of ASCUS, in spite of a 17.5% CIN rate, remains unknown, but constitutes a high-risk group.