The clinical value of viral load and integration testing for human papillomavirus (HPV) remains unclear. Data on HPV type 18 (HPV18) is limited. We examined the HPV18 viral load and integration status of 78 women with normal cervix or neoplasia. While the crude viral load appeared to increase with lesion severity, the association was not significant after normalization with sample cellularity. Unlike reports for HPV16, the amino-terminal 1 region of HPV18 E2 was most frequently (71.0%) disrupted, representing the best marker for integration. A substantial proportion (57.1%) of invasive cancers harbored only the episomal genome, thus jeopardizing the clinical value of integration testing. A large proportion (41.7%) of normal/low-grade lesions showed viral integration, suggesting that integration of HPV18 starts early and is unlikely to be a sole determinant for progression. Interpretation of viral load should take into account the form of HPV infection as single infections had significantly higher viral loads than coinfections (P ؍ 0.046). More data generated from routinely collected samples are warranted to verify the clinical value of viral load and integration testing. Viral load quantitation for HPV18 is premature for clinical use at this stage.There is no doubt that infection with human papillomavirus (HPV) may lead to the establishment of cervical cancer (3, 33). Though infection with HPV is common, not all HPV types will lead to cancer. There are 15 high-risk HPV types that have a higher propensity for the development of cervical cancer, with HPV type 16 (HPV16) and HPV18 being the most prevalent high-risk types worldwide (8,25).Women who have tested positive for high-risk HPV tend to harbor abnormal cervical cytology, and some studies have reported a correlation between viral load and disease severity (19,20,24,28,31). However, the consistency of these findings has been questioned, and it is now realized that the relationship is a lot more complex (5-7, 35). As the severity of disease increases, HPV is often found integrated into the host genome, making the interpretation of viral load even more complex. Furthermore, the available viral load data have been generated using different methodologies that may not be directly comparable (13,17,28,29).The HPV genome can exist in two physical forms: a closed circular episomal form or linearized and integrated into the host genome. Integration of the viral genome is often associated with the disruption of the E2 gene, which has regulatory control of the oncogenes E6 and E7. Nevertheless, this concept has been questioned by a recent study where the integration of the HPV16 genome was not necessarily associated with the overexpression of E6 and E7 (14). HPV18 has been found to be strongly associated with adenocarcinoma of the cervix. Studies carried out with HPV18 have shown that the viral genome is almost invariably found to be integrated in highgrade cervical intraepithelial lesions and invasive cancers (2,9,22,27,32), and these findings potentially allow the us...