BACKGROUND. The American Society for Colposcopy and Cervical Pathology recently recommended triage of women with atypical squamous cells of undetermined significance (ASCUS) through reflex human papilloma virus (HPV) infection testing. Because age is an important determinant of the incidence of both ASCUS and HPV infection, the current study was conducted to determine the impact of age on reflex HPV infection test performance. METHODS. The authors reviewed all liquid-based Papanicolaou tests submitted for reflex HPV infection testing to the University of Alabama Medical Center during the period from January 2002 to January 2004. To assess the impact of age on reflex HPV infection testing, women were divided into 6 age groups (< 25, 25-34, 35-44, 45-54, 55-64, >64 years). Trend of different diagnostic categories with age was assessed using the chi-square test for linear trend. As a measure of test performance, the proportions of cervical intraepithelial neoplasia (CIN) lesions confirmed by biopsy through reflex testing (of the total CIN lesions detected in the study population) were then compared among different age groups. RESULTS. During the study period, 25,164 ThinPrep tests were performed during the study period, with 2672 (11%) cases of ASCUS and 1371 (5%) cases of squamous intraepithelial lesions (SILs). A total of 2309 (86%) ASCUS cases were tested for HPV infection, of which 789 (34%) were positive. Biopsy specimens were obtained from 831 patients with SILs and from 316 patients with HPV+ASCUS. Of 246 patients with CIN Grade 2-3 (CIN2-3) detected on biopsy, 36 (15%) were triaged through reflex HPV infection testing and the rest were triaged through cytologic diagnosis of SILs. Despite the trend in the prevalence of HPV+ASCUS and SILs with increasing age (P < 0.05), there was no significant difference in the proportion (range, 9-23%) of CIN2-3 detected through reflex HPV infection testing in different age groups. CONCLUSIONS. Reflex HPV infection testing performed similarly for women in different age groups, including perimenopausal and postmenopausal women. © 2005 American Cancer Society.