Microestructural characterization of sintered niobium obtained by solid-state sintering of powders with distinct granulometries was performed. The influence of using powders with different particle sizes was analyzed by determining both the volume fraction of pores and grain size after sintering at 1900°C and 2000°C for distinct holding times. The densification curves show the decrease of the porosity which levels off at about 3.0% for samples made with the powder sizes -200+270# and -635# (mesh). The results are in good agreement with those reported in the literature.