The present invention relates to an improved single crystal nickel base superalloy and a process for making same. The single crystal nickel base superalloy has a composition comprising 3 to 12 wt % chromium, up to 3 wt % molybdenum, 3 to 10 wt % tungsten, up to 5 wt % rhenium, 6 to 12 wt % tantalum, 4 to 7 wt % aluminum, up to 15 wt % cobalt, up to 0.05 wt % carbon, up to 0.02 wt % boron, up to 0.1 wt % zirconium, up to 0.8 wt % hafnium, up to 2.0 wt % niobium, up to 1.0 wt % vanadium, up to 0.7 wt % titanium, up to 10 wt % of at least one element selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, platinum, and mixtures thereof, and the balance essentially nickel. The single crystal nickel base superalloy has a microstructure which is pore-free and eutectic .gamma. .gamma.' free and which has a gamma prime morphology with a bimodal .gamma.' distribution.