In this work, the longitudinal tensile and compressive properties of TOHO HTS 40 carbon fiber filaments was characterized experimentally. The tensile strength and modulus were measured using a single filament tension tests using gage lengths ranging between 0.5 inches to 3 inches. The compression strength was measured using a loop test. The measured tensile modulus had an average value of 192 GPa across gage lengths and did not exhibit significant dependence on the gage length. The average tensile strengths at each gage length exhibited the well-known length effects, with the strength decreasing from an average value of 4 GPa at a gage length of 0.5 inches to 2.52 GPa at a gage length of 3 inches. The average compression strengths from the loop tests was found to be 3.86 GPa.