The effect of atmosphere control on the sintering behaviour of TiB2-20 wt % Ni ceramics was investigated. Sintering was performed at 1700 degrees C for 1 h with commercial TiB2 powders produced by the carbothermic reaction. Under a fixed single atmosphere such as vacuum or Ar, densification was limited and large pores remained. However, a sintered density above 99% of theoretical could be achieved by a two-step sintering procedure in which the atmosphere was changed from vacuum to Ar at 1600 degrees C during the heat-up with subsequent isothermal sintering being performed at 1700 degrees C for 1 h. Qualitative considerations about these phenomena are discussed.