Introduction: The term atypical squamous cells of undetermined significance refers to cytological changes suggestive of low-grade intraepithelial lesion that are insufficient for a definitive interpretation. In our region, there are no studies evaluating the frequency of dysplastic lesions in patients with atypical squamous cells of undetermined significance and there is no certainty about the most appropriate management. Aim: To describe the histopathological findings in biopsies or conizations performed after a diagnosis of atypical squamous cells of undetermined significance was made on cytology, and to determine the need for biopsy in these patients. Materials and Methods: We conducted a retrospective study of cases archived in the Department of Pathology for the year 2010. We included and reviewed all the cervical biopsies and conizations performed after a cytological diagnosis of atypical squamous cells of undetermined significance. For these cases, demographic data and histological findings were assessed. Results: During 2010, a total of 271 cervical histological studies were performed after a cytological diagnosis of atypical squamous cells of undetermined significance was given. In 25.1% of the patients the histological diagnosis was low-grade intraepithelial lesion; in 6.3% high-grade lesions were diagnosed, whereas in 68.6% of patients dysplasia was not found. Conclusions: Many patients with atypical squamous cells of undetermined significance have intraepithelial lesions and they should be studied with colposcopy or biopsy, or followed with periodic cytology. The proportion of patients with high-grade lesions was lower than the reported in other countries, which suggests the need to assess the quality of cervical cytology in our region.