The high-temperature deformation behavior of a SiC whisker-reinforced, yttria-stabilized, tetragonal zirconia polycrystalline composite containing 20 vol % SiC whiskers (SiC/Y-TZP) has been investigated. Tensile tests were performed in vacuum at temperatures from 1450 °C to 1650 °C and at strain rates from 10−3 to 10−5 s−1. The material exhibits useful high-temperature engineering properties (e.g., ∼100 MPa and 16% elongation at T = 1550 °C and at a strain rate of ∼10−4 s−1). The stress exponent was determined to be n ≍ 2. Scanning electron microscopy was used to characterize the grain size and morphology of the composites, both before and after deformation. The grain size in the composite was initially fine, but coarsened at the test temperatures; both dynamic and static grain growth were observed. The morphology of ceramic reinforcements appears to affect strongly the plastic deformation properties of Y-TZP. A comparison is made between the properties of monolithic Y-TZP, 20 wt. % Al2O3 particulate-reinforced Y-TZP (Al2O3/Y-TZP), and SiC/Y-TZP composites.