A method is proposed to detect the presence of a uniaxial stress component in samples belonging to the cubic system, pressed in a tungsten carbide anvil x-ray camera unit. The method is based on fitting the experimental data to an expression of the form Єw(hkl)=Єwp-m t(C11+4C12-2C44)/2 (C11+2C12)(C11-C12+3C44)+n t [S12+(S11-S12-S44/2) Γ(hkl)], where Єw(hkl) is the strain calculated from the shift of the diffraction line (hkl) at a load w applied between the anvils, Єwp is the strain arising from the hydrostatic component of the stress p, t is the uniaxial stress component, and Γ(hkl)=(h2k2+k2l2+l2h2)/ (h2+k2+l2)2. If the state of stress continuity in the crystallites is assumed, then m =0 and n =1; and m =1 and n =0 if the state of strain continuity in the crystallites is assumed. The experimental data for Si at w = 1400 kg and for NaCl at w = 510 kg indicate a linear dependence of Єw(hkl) on Γ(hkl) as is expected for n ≠0. The slope of the Єw(hkl) versus Γ(hkl) plot is negative for Si and positive for NaCl; this is in agreement with the theory as the value of (S11-S12-S44/2) is positive for Si and negative for NaCl, and t, being a compressive stress, is negative by convention. The lowest estimates of t, made from the slope of the Єw(hkl) versus Γ(hkl) plot, is obtained if m =0 and n =1 are assumed. The slope of the Єw(hkl) versus Γ(hkl) plot shows a considerable variation from run to run. For Si, for example, the l owest estimate of t varied between 21±4 and 32±4 kbar in the four runs made at w = 1400 kg. For NaCl, the lowest estimate for t varied between 4.2 ± 1.5 and 5.5 ± 1.5 kbar in the six runs made at w = 510 kg.