Background: Anogenital warts (AGWs) are common results of sexually transmitted infection (STI). Human papillomavirus (HPV) types 6 and 11, which are non-oncogenic types, account for 90% of the clinical manifestations. Although the quadrivalent HPV vaccine has been launched, AGW remains prevalent in some countries and shows association with abnormal cervical cytology. Objectives: To study the prevalence of abnormal cervical cytology (low grade squamous intraepithelial lesions or worse; LSIL+) in immunocompetent Thai women newly presenting with external AGWs. Materials and Methods: Medical charts of all women attending Siriraj STI clinic during 2007-2011 were reviewed. Only women presenting with external AGWs who were not immunocompromised (pregnant, human immunodeficiency virus positive or being on immunosuppressant drugs) and had not been diagnosed with cervical cancer were included into the study. Multivariate analysis was used to determine the association between the characteristics of the patients and those of AGWs and LSIL+. Results: A total of 191 women were eligible, with a mean age of $27.0{pm}8.9$ years; and a mean body mass index of $20.6{pm}8.9kg/m^2$. Half of them finished university. The most common type of AGWs was exophytic (80.1%). The posterior fourchette appeared to be the most common affected site of the warts (31.9%), followed by labia minora (26.6%) and mons pubis (19.9%). The median number of lesions was 3 (range 1-20). Around 40% of them had recurrent warts within 6 months after completing the treatment. The prevalence of LSIL+ at the first visit was 16.3% (LSIL 12.6%, ASC-H 1.1%, HSIL 2.6%). After adjusting for age, parity and miscarriage, number of warts ${geq}5$ was the only factor associated with LSIL+(aOR 2.65, 95%CI 1.11-6.29, p 0.027). Conclusions: LSIL+ is prevalent among immunocompetent Thai women presenting with external AGWs, especially those with multiple lesions.