This paper discusses determination of threshold stress intensity factor (KIscc) and crack growth rate of austenite stainless steel in 42 wt.% MgCl2 environment at 154 °C using the circumferential notch tensile (CNT) technique. The KIscc and crack growth rate of solution annealed and sensitized AISI 304 stainless steel in chloride environments have been determined using the CNT technique. Valid KIscc data have been produced and compared with results obtained by compact tension and double cantilever beam methods. The KIscc of sensitized stainless steel is ∼50% lower than the solution annealed AISI 304 stainless steel. This work investigated the applicability of the CNT technique to determine the KIscc of thin and narrow sections of solution annealed and sensitized stainless steel in the chloride environment. This paper also discusses the mechanistic aspects of the difference in fractographic features of the sensitized and solution annealed stainless steel.