We present fracture toughness measurements conducted on Hydrogen-free tetrahedral amorphous Diamond-like Carbon (ta-C) MEMS-scale specimens with thickness in the range of 0.5 - 3μm. Edge pre-cracks were generated in uniform gage specimens via microindentation of the supporting SiO 2 sacrificial layer. One of the indentation cracks propagated in the SiO 2 layer and into the ta-C specimen generating a mathematically sharp crack. The precise crack length was determined using an Atomic Force Microscope (AFM). The pre-cracked specimens were released from the sacrificial SiO 2 via wet etch and mode-I micro-tensile tests were performed on the freestanding specimens. Since ta-C is perfectly brittle the mode-I fracture toughness K IC was computed using the linear elastic fracture mechanics solution (LEFM). K IC was found to be 4.25 ± 0.7 MPa√m for 0.5 μm specimens, 4.4 ± 0.4 MPa√m for 1 μm specimens, and 3.06 ± 0.17 MPa√m for 3 μm specimens. Unlike macroscale specimens, this thickness dependence of fracture toughness is not attributed to a plane stress state. Rather, the observed trends may have arisen from through-the-thickness compositional variations and residual stresses.