In this work, the effects of cobalt content and C/W ratio on grain growth are studied, in order to better understand the mechanisms. Powder compacts were sintered at 1410 degrees C for 1 and 5h. The relative contribution of carbide dissolution in the binder and grain growth for the evolution of the size distribution is discussed. Grain size measurements were made with the Electron BackScattered Diffraction technique. The distribution of 2D equivalent disk diameters was converted in a distribution of 3D equivalent sphere diameters, with the Saltykov method. High cobalt content favors grain growth in W-rich samples whereas it has a slight influence on C-rich samples. But still grain growth is significantly faster in C-rich samples. Variation in the D-90/D-10 ratio indicates a tendency to abnormal growth, with a broadening of the size distribution between 1 and 5h, favored by high binder content.