The stress corrosion of two AISI 304 and one AISI 316 stainless steels, fully austenitized and at two different sensitization degrees, has been studied in NaCl solutions and synthetic sea water at 80°C. Measurements were made at a constant strain rate of 1 × 10−6s−1 under free corrosion as well as under controlled potential conditions. The changes in nominal stress were determined as a function of time, at various potential values, on samples on which an attack has been induced. Pitting potentials in 0.1 M NaCl were measured for all materials. All the stainless steels examined, sensitized at 650°C for 24 h, exhibit a marked susceptibility, in 0.1 M NaCl solutions and sea water, to transgranular SCC. After sensitization at 650°C for 1 h only one of the AISI 304 steels, with a C content of 0.073%, shows intergranular stress corrosion cracking (IGSCC). The measurements at controlled potential allowed determination of potential values below which no IGSCC occurs. The more negative these potentials are, the greater the susceptibility to IGSCC. Comparison of the pitting potentials with the potentials at which IGSCC occurs showed that IGSCC and pitting are two distinct phenomena in the case of highly sensitized samples. In other cases it cannot be excluded that IGSCC may originate from pitting.