The aim of this study was to determine the proportion of invasive cervical cancers attributable to human papillomavirus (HPV) types 16 and 18 in a contemporary, cytologically well-screened UK population. This was achieved in a retrospective observational analysis by HPV typing 453 archival invasive cervical cancers diagnosed between January 1, 2000 and September 1, 2006. Pathological material was collected from 9 hospitals across Wales (UK), and HPV typing and pathology review was conducted at a central laboratory. Genotyping for high-risk HPV DNA was performed by PCR-enzyme immunoassay using the GP5+/6+ primer set. DNA was successfully extracted from 297 cases. Two hundred and eighty cases were included in the final analysis. The proportion of cases which had only HPV 16 and/or 18 was 219 of 280 (78.2%, 95% CI = 73.0-82.7); the proportion of cases which had HPV 16 or 18 and another HPV type was 230 of 280 (82.1%, 95% CI = 77.2-86.2). The proportion of cervical cancers associated with infection with HPV types 16 and 18 has previously been estimated at around 70%. The appropriate figure for a cytologically well-screened UK population appears to be approximately 80%. Hence, the potential impact of the current vaccination programme may be underestimated.