The densification and grain growth behavior of powder injection molded 316L stainless steel micro-nanopowder were investigated in terms of microstructural development. The sintered density of the micro-nanopowder sample increased remarkably in the temperature range of 1000 to 1100 degrees C due to the sintering effect of nanopowders which increased the number of grain boundaries acting as high material transport path. A near full density of 98% TD was obtained after sintering at 1100 degrees C for 5 h with the average grain size less than 10 pm, indicating that there was no drastic grain growth. The presence of nanopowders in micro-nanopowder played decisive role in the entire sintering process by enhancing densification but suppressing grain growth. These effects open up the possibility of using micro-nanopowder feedstock to control the sintering behavior of powder injection molding products with full density and fine microstructure. (C) 2015 Elsevier B.V. All rights reserved.