The formation of nitrogen gas pores is affected by various factors such as solidification sequence, solubility of nitrogen, cooling rate, melt pressure, nitrogen content etc. Nitrogen porosity in Fe-16Cr-3Ni-9Mn austenitic stainless steel solidifying to primary delta-ferrite that can cause nitrogen gas pores was examined. And also the effect of nitrogen content, cooling rate and melt pressure on nitrogen porosity was investigated.