Background: To evaluate colposcopic biopsy results of patients with cervical cytological findings of atypical squamous cells of undetermined significance (ASC-US) and atypical squamous cells with high-grade lesions that cannot be excluded (ASC-H). Materials and Methods: A retrospective evaluation of data from 358 patients, who had cervical cytological findings of ASC-US (n=335) and ASC-H (n=23), and had colposcopic assessments between 2005 and 2011. Results: Cervical biopsy results of patients diagnosed with ASC-US cytology (n=335) revealed cervical squamous cell carcinoma 0.9 % (n=3) at biopsy, cervical intraepithelial neoplasia 3 (ON 3) in 3.8 % (n=13), cervical intraepithelial neoplasia 2 (CIN 2) in 1.1 % (n=4), cervical intraepithelial neoplasia 1 (CIN 1) in 35.2 % (n=118), and benign lesions in 59% (n=197). Cervical biopsy results of patients diagnosed with ASC-H cytology (n=23) revealed CIN 3 at biopsy in 39.3% (n=9), CIN 2 in 21.7% (n=5), CIN 1 in 26% (n=6), carcinoma in situ in 8.7% (n=2), and squamous cell cancer in one patient (4.3%). Conclusion: The cytological diagnosis of ASC-US may lead to the diagnosis of cervical intraepithelial lesion of higher grades as well as cervical cancer and should be evaluated by colposcopic cervical biopsy.