The evolution of the strain-induced α′ martensite during the cyclic deformation of austenitic AISI 316L stainless steel (SS) was investigated. The low-cycle fatigue (LCF) test was conducted at various strain amplitudes in air. The amount of α′ martensite was determined for the fatigue-failed specimens as well as for the specimens interrupted after a specific number of cycles. The volume fraction of α′ martensite increased with increasing strain amplitude and number of fatigue cycles. The cyclic hardening behavior was discussed in terms of the dislocation density and strain-induced α′ martensite transformation.