This report summarizes the present knowledge concerning the relationship among fabrication history, metallurgical structure, and the mechanical properites of the refractory metals columbium, tantalum, bolybdenum, and tungsten, and their alloys. These are the refractory metals currently reveiveing the most attention for aerospace applications, and are therefore the materials considered in this survey. The report is organized into three main sections, titled ''Fabrication'', ''Microstructure and Alloying'', and ''Interstitial Impurities''. The data presented were selected as those which best illustrate the topics discussed. Descriptions of the metaljurgical principles involved are included. Suggestions for optimizing mechanical properties by controlling metallurgical structure are made where possible. (Author).