We report on a novel class of semiconductor metamaterials that employ a strongly anisotropic dielectric function to achieve negative refraction in the midinfrared region of the spectrum, ∼8.5–13 μm. We present two types of metamaterials, layered highly doped/undoped heterostructures and quantum well superlattices that are highly anisotropic. Contrary to other optical metamaterials these heterostructure systems are optically thick (up to 20 μm thick), planar, and require no additional fabrication steps beyond the initial growth. Using transmission and reflection measurements and modeling of the highly doped heterostructures, we demonstrate that these materials exhibit negative refraction. For the highly doped quantum well superlattices, we demonstrate anomalous reflection due to the strong anisotropy of the material but a determination of the sign of refraction is still difficult. This new class of semiconductor metamaterials has great potential for waveguiding and imaging applications in the long-wave infrared.