In 1988, The Bethesda System for reporting cervical and vaginal cytologic diagnoses was introduced and this was revised in 1991. The new diagnostic category "atypical squamous cells of undetermined significance(ASCUS)" introduced by The Bethesda System is an area of controversy about the diagnostic category, clinical significance and appropriate treatment. A retrospective 2 years and 9 months study(April, 1994-December, 1996) was performed to evaluate the significance of reporting ASCUS on cervical smears. Sixtyseven(1.17%) of 5,730 smears were diagnosed as ASCUS and 21 cases were followed by cervical biopsies and/or endocervical curettages in 4 cases(19%), and repeat cervical smears in 17 cases(81%). Tissue diagnoses were benign in 2 cases and squamous cell carcinoma in situ in 2 cases. Cytologic diagnosis of follow up smear were negative in 14 cases(82.4%) and persistent ASCUS in 3 cases(17.6%).