The creation of defects and radiation-induced segregation (RIS) in single crystals of type 304 stainless steel, 1.6 MeV He irradiated up to 2.5 × 10 17 cm −2 at RT, has been investigated by using a combination of RBS and PIXE with channeling (RBS-C and PIXE-C). From the RBS-C, it is found that radiation-induced defects for 〈110〉 orientation increased more slowly with irradiation dose from those for the 〈100〉 and 〈111〉 orientations. The PIXE-C measurements show that Si atoms segregate to the (100), (110) and (111) surfaces and S atoms seem to enrich slightly in the (100) and (110) surfaces during 1.6 MeV He ion irradiation. It is the first time that the phenomenon of radiation-induced segregation is observed in stainless steels at room temperature irradiation.