Objective To determine the distribution of human papillomavirus (HPV) genotypes in cervical adenocarcinoma in Thailand and to evaluate the clinicopathologic characteristics associated with common HPV genotypes. Methods Formalin-fixed, paraffin-embedded tissues from 150 patients with adenocarcinoma were collected from 4 areas of Thailand. Infection with HPV was detected by nested polymerase chain reaction (PCR) with primers MY09/11 and GP5 +/6 +. Genotyping was performed using a linear array assay, followed by type-specific PCR targeting the E6/E7 regions of HPV-16, HPV-18, and HPV-52 if the linear array test was negative. Results Human papillomavirus DNA was detected in 145 (97%) adenocarcinomas (132 single infections; 11 multiple infections; 2 tumors with undetermined HPV type). Genotype 18 was most common (66%), followed by HPV-16 (30%) and HPV-45 (3%). Infection with only HPV-16 and/or HPV-18 accounted for 88% of the HPV-positive tumors. Patients with HPV-18 infection had a younger age (P = 0.009) and higher tumor grade (P < 0.001) than patients with HPV-16 infection. Conclusion The HPV detection rate in cervical adenocarcinomas in Thailand is high. The predominant genotype is HPV-18, being twice as common as HPV-16. Genotype variations are associated with patient age and tumor grade. Vaccination against HPV-16/HPV-18 might prevent almost 90% of adenocarcinomas. © 2013 International Federation of Gynecology and Obstetrics.