Meta-analysis is a systematic and objective methodology for synthesizing research literature. The authors present the history and definition of meta-analysis, discuss the generic framework for design and implementation of a meta-analysis, and review the problems and pitfalls that can accompany meta-analyses. Their discussion draws on practical experience with several meta-analyses of the low back pain literature. Meta-analysis can be used to help answer the questions about various options for diagnosis and treatment of low back problems and also to point out gaps in our knowledge base that may have a high priority for research. Meta-analytic methods are an informative means of addressing health care controversies with major patient management and cost implications.