The VMS version of PREPRO2004 comes with executable codes, in compressed form. 1) To uncompress and install, copy INSTALL.BAT and PREPROZ.EXE to your hard drive. Execute INSTALL.BAT - WARNING - DO NOT execute PREPROZ.EXE, or the system will not properly install into a directory structure. After installation you can delete PREPROZ.EXE and INSTALL.BAT. 2) To VERIFY proper installation, it is recommended that after installation you execute VERIFY. This is a batch file that will run the codes in sequence. The final two codes will display the calculated cross sections (EVALPLOT), and compare the results you calculated to a standard set of results (COMPLOT). Difference of about 1 % are acceptable; larger differences indicate an installation problem. 3) If you have any problems notify the Nuclear Data Section, IAEA, Vienna, Austria. services@iaeand.iaea.or.at