This paper discusses a method for calculating the "true" undrained strength ratio, (cu/p)ss, and the internal friction angle, φ\u27ss, in terms of effective stress of normally consolidated clays measured in a simple shear test. The proposed method consists in assuming that the directions of the principal stress axes during the simple shear test are expressed by the relation proposed by Oda and Konishi. Experimental results obtained from three types of clays confirm that the method gives more reasonable estimates of (cu/p)ss and φ\u27ss for normally consolidated clay compared to other methods. The method also supports Ladd\u27s statement that (cu/p)ss should generally be less than (cu/p)TC determined from the triaxial compression test due to undrained strength anisotropy. Finally, a significant disadvantage of the method proposed by Duncan and Dunlop is discussed, and it is pointed out that the Duncan and Dunlop method may predict excessively high values of φ\u27ss for normally consolidated clay
