The capture-recapture method allows, by cross-referencing multiple sources of information from the same population, for estimating the number of cases not identified by any of the sources, the total number of cases (N) of the disease, and thus the completeness of each source. Used in zoology and demography, this technique has been applied to epidemiology for the past twenty years. Its application requires that six conditions be met: all cases identified by the sources are true cases; they occurred during the study period and within the study area; the study population is closed; all common cases and only common cases are identified; the sources are independent of one another; and there is homogeneity in case capture. Accounting for dependence among sources is possible only if more than two sources are available using the log-linear model; however, interactions of the highest order cannot be controlled. Since failure to meet certain application conditions can significantly bias estimates, it is recommended to use correction methods. The study on estimating the number of collective foodborne salmonella outbreaks illustrates the full application of these methods. Often using data collected for purposes other than estimating case numbers, the capture-recapture method is exploratory or serves to validate an estimate of the number of cases of a given disease. It should not be used as a substitute for sampling or exhaustive approaches simply because it is more cost-effective. However, this method is very useful for assessing the completeness and representativeness of surveillance systems and registries.