Dear XRDA potential and present users, XRDA, a program for energy-dispersive diffraction analysis on the PC which runs under Windows (3.1 and 95), is now available to the scientific community. Although the program is mostly suited for energy-dispersive X-ray diffraction using synchrotron radiation, it can conveniently be used for general peak profile fitting. For instance, XRDA is our standard tool to fit lines obtained by Raman spectroscopy. The current XRDA release is labelled 3.1. It is an improved and augmented program as compared to version 1.0 which we reported in a paper published in J. Appl. Cryst. 27, 432 (1994). Version 3. contains a help document, accessible within the program, which describes briefly the different features and procedures. In a true spirit of scientific collaboration, XRDA is being distributed as shareware. It is available via anonymous ftp at "joule.physics.uottawa.ca" in /ftp/pub/lpsd/xrda. The "readme.txt" file gives instructions on how to download all the necessary files. Although XRDA is free of charge, a monetary contribution* would be appreciated if you feel that XRDA is an useful tool for your work and that its development should be pursued. A reference to the J. Appl. Cryst. 27, 432 (1994) is necessary if XRDA is used in the course of a published research work. Thank you for your interest in XRDA. Comments will be gladly received. Yours, Prof. Serge Desgreniers. serge@physics.uottawa.ca * Suggested contribution : $110 US. or $150 CAN (Visa or MC payments may also be arranged) Send your contribution to: Prof. Serge Desgreniers Department of Physics University of Ottawa 150 Louis Pasteur Ottawa, Ontario ,Canada K1N 6N5