When abbreviations are used in medical papers, in the recording of case histories or physical examinations or in operative or pathologic reports, the meaning should be entirely clear to all who may have occasion to read them. This is not, of course, the case. Abbreviations of medical terms are used obviously to save the time of the writer; too often, however, the time thus saved is wasted many times over by the person who is trying to decipher the meaning originally intended. When placed within a context, many of the abbreviations commonly employed in medicine are reasonably clear to those intimately familiar with the particular field; but when removed from such environment they become even more abstruse. Few readers for example can probably identify with ease such fairly commonly employed abbreviations as M. T. R., PcB, P. P. D., M. E. D., s. e. d., M. K. R. or K.