An experimental method for the construction of yield surfaces for metal matrix composites is presented. Tubular specimens are subjected to axial-torsion loading. Multiple probes and multiple runs can be conducted on a single specimen. Offset strains are used to unload yield surface probes, but permanent strains are used to determine yield points. Initial and subsequent yield surfaces are obtained for aluminum alloy 6092 reinforced with silicon carbide particles having a 0.175 particle volume fraction and for aluminum reinforced with alumina fibers having a 0.55 fiber volume fraction. The fibrous composites tested are OE04-, OE904-, OE0=90-2 laminates. All yield loci are ellipses in the axial-shear stress plane. Subsequent yield surfaces exhibit significant translational hardening.