Several studies suggest that HPV testing is more sensitive than cytology in primary cervical screening. These studies had different designs and were reported in different ways. Individual patient data were collected for all European and North American studies in which cytology was routinely performed and HPV testing was included as an additional parallel test. More than 60,000 women were included. The sensitivity and specificity of HPV testing were compared with routine cytology, both overall and for ages <35, 35-49 and 50+. The age-specific prevalence of high risk HPV (hr-HPV) was also analysed. HPV testing was substantially more sensitive in detecting CIN2+ than cytology (96.1% vs. 53.0%) but less specific (90.7% vs. 96.3%). The sensitivity of HPV testing was similar in all studies carried out in different areas of Europe and North America, whereas the sensitivity of cytology was highly variable. HPV sensitivity was uniformly high at all ages, whereas the sensitivity of cytology was substantially better in women over the age of 50 than in younger women (79.3% vs. 59.6%). The specificity of both tests increased with age. Positivity rates for HPV testing in women without high-grade CIN were region dependent. These results support the use of HPV testing as the sole primary screening test, with cytology reserved for women who test HPV positive. Large demonstration projects are needed to fully evaluate this strategy.