To find the sensitivity, specificity, and positive and negative predictive values of the high-risk group human papillomavirus (HPV) DNA testing as a triage tool to detect high-grade squamous intraepithelial lesions (HSILs, ie, cervical intraepithelial neoplasia [CIN] 2 or worse) in women with a cytologic smear showing atypical squamous cells of undetermined significance (ASC-US). All new cases with cytologic smears showing ASC-US that presented in King Chulalongkorn Memorial Hospital from January 2003 to November 2003, excluding known cases of HSILs and pregnancies, were enrolled. Cervical cell samplings were done by cervical cytobrush technique and tested for high-risk group HPV with the Hybrid Capture 2 (HC2) test. All participants were examined under a colposcope. Then cervicographs were taken before colposcopic-directed cervical biopsies were done. Of the 90 ASC-US cases enrolled, the pathologic results were normal in 30.0%, squamous metaplasia in 16.7%, CIN 1 in 37.8%, CIN 2 in 1.1%, CIN 3 in 11.1%, and microinvasive cervical carcinoma in 3.3%. The prevalence of HSILs and the prevalence of high-risk HPV detection were 15.6% and 38.9%, respectively. Using pathologic results from cervical biopsy as the gold standard, the HC2 has the sensitivity, specificity, and positive and negative predictive values of 85.7%, 69.7%, 34.3%, and 96.4%, respectively, to detect HSILs. High-risk group HPV detection can be used as an additional triage test to detect HSILs in women having ASC-US with high sensitivity and negative predictive value.