Binderless tungsten carbide (WC) with 0.1, 0.4, and 1.2 μm powder size was sintered successfully by field assisted sintering technology (FAST). Density values above 98% were achieved at 1500oC under 65 MPa pressure. The relative density of sintered 0.1 μm WC powder was around 97% with hardness value as high as 95-96 HRA. WC-6wt.%Co with 4 μm powder size was sintered to 99% relative density at relatively low temperature, 1280oC, (100-200oC lower than that of pressureless sintering). Significant increase in hardness (3-4 HRA) was observed. By addition of nano WC powder in WC-6wt.%Co, the hardness value was improved, while fracture toughness decreased slightly. It is shown that engineering the microstructure of WC materials is possible by mixing initial powder sizes, then sintering in FAST.