An important but largely ignored problem in using museum specimens of bats in morphometric studies is that changes are induced in the specimens during the preservation process. Values obtained from preserved specimens may thus differ markedly from those obtained from the living animal. A brief diagnosis of this problem in dealing with chiropteran specimens is presented, as is a summary of the current knowledge dealing with potential changes during preservation of study skins and alcoholic chiropteran specimens. Finally, it is suggested that a standardized procedure for obtaining wing tracings be used by specimen collectors, museums, and chiropteran researchers to alleviate or at least minimize these problems for bat specimens.