Studies of nerve regeneration in rodents utilize at least one of three classes of outcome measures: electrophysiology, morphometry, and functional tests. The assumption that these measures are correlated was tested utilizing a data set of 16 variables. Significant correlations (Spearman's rho, P < or = 0.05) were found within variable classes; however, none were found between classes. The three commonly utilized outcome measures do not measure the same phenomenon but rather discrete aspects of nerve regeneration.