To introduce guidelines for the conduct, reporting, and critical appraisal of meta-analyses evaluating diagnostic tests and to apply these guidelines to recently published meta-analyses of diagnostic tests. Based on current concepts of how to assess diagnostic tests and conduct meta-analyses. They are applied to all meta-analyses evaluating diagnostic tests published in English-language journals from January 1990 through December 1991, identified through MEDLINE searching and by experts in the field. Meta-analyses were included if at least two of three independent readers regarded their main purpose as the evaluation of diagnostic tests against a concurrent reference standard. By three independent readers on the extent to which meta-analyses fulfilled each guideline, with consensus defined as agreement by at least two readers. The guidelines are concerned with determining the objective of the meta-analysis, identifying the relevant literature and extracting the data, estimating diagnostic accuracy, and identifying the extent to which variability is explained by study design characteristics and characteristics of the patients and diagnostic test. In general, the guidelines were only partially fulfilled. Meta-analysis is potentially important in the assessment of diagnostic tests. Those reading meta-analyses evaluating diagnostic tests should critically appraise them; those doing meta-analyses should apply recently developed methods. The conduct and reporting of primary studies on which meta-analyses are based require improvement.