Diagnostic Accuracy: Seventeen reports on 13 unique trials undertaken in nine countries met the selection criteria for comparing LBC and Pap smears; 23 unique trials met the criteria for comparing HPV testing and Pap smears. Interpretation of the results is hampered by the failure of some trials to meet several validity criteria: in particular, not all women received the reference test. Evidence (based primarily on results from split-sample trials) suggests that compared with Pap smears, the use of LBC reduces the proportion of unsatisfactory specimens and generates fewer false negatives for ordinary populations, but not for high-risk populations. HPV testing, alone or with cytology, is more sensitive but less specific than Pap smears.