Abstract: A structure for the root portion of a turbine blade and for the attachment grooves on a turbine rotor in conjunction with blades having integral shrouds and platforms as well as blades which are not attached to one another, blades which are joined by nonintegral shrouds and blades which do not include platforms. The invention is applicable to straight side entry blade roots and rotor grooves as well as curved side entry blades and curved rotor grooves. The invention results in reduced stress levels in the blade attachment structure by decreasing the land widths and increasing the fillet radii of curvature associated with each tang on a turbine blade root. In addition, the fillet radii of curvature are individually dimensioned to more uniformly distribute stress levels among blade root tangs. The reduction in land widths is accomplished by increasing land contact stresses for a given blade design.