Among compression test methods for composites, ASTM D3410, SACMA SRM 1R-94, and ASTM D6641 are currently used to determine the compression modulus, E 11c, for ultra-high modulus (UHM, > 350 GPa) composites. In this study, the compressive modulus of a UHM carbon/epoxy composite specimen is experimentally determined via SACMA SRM 1R-94 and ASTM D6641; ASTM D3410 is excluded from the study due to test fixture assembly complexities. A finite element model is developed for each experimental method to calculate the compression modulus of the UHM carbon/epoxy composite. The largest strains are found to be at the specimen ends for SACMA SRM 1R-94 and in the adhesive at the gage end for ASTM D6641. A statistical sensitivity analysis (ANOVA) is used to vary parameters suspected to influence the compression modulus of the UHM carbon/epoxy composite specimen for ASTM D6641. It is found that the compression modulus of the UHM carbon/epoxy composite specimen is most sensitive to the clamping pressure due to bolt torque in the ASTM D6641 test fixture and the UHM specimen thickness.