This bulletin reviews@ evaluates@ and summarizes the recent development and current knowledge of ??-strengthened nickel base cast superalloys. Since the publication of SuperalIoys II by Sims@ Stoloff@ and Hagel in 1987@ there have been great advancements in the alloy development@ manufacturing@ coating@ and repair of ??-strengthened nickel-base superalloys. Wider use of single crystal and directionally solidified superalloys in newer industrial turbines has prompted more effort in welding@ repair@ and properties assessment. The most representative for each aspect of this complex family of alloys is selected for study from the vast amount of literature@ including those that are most widely used in today's industry. The representative alloys under this category include IN738@ GTD-111@ PWA-1480@ CMSX-4@ and other newer single crystal superalloys. Special emphasis has been given to the metallurgy and properties evaluation of these superalloys. This bulletin serves as a supplement to SuperalIoys II by providing an update on this fascinating class of engineering alloys. Wrought nickel base superalloys which contain less amount of ?? cobalt base superalloys@ ceramic materials@ and intermetalics are not included