The fatigue properties of ferritic stainless steel containing deformation twins were investigated. Monotonic tensile tests and push-pull fatigue tests were conducted on the specimens both with and without twins. Fatigue lives of the twinned specimens were about four times shorter than those without the deformation twins, although yield stresses of both specimens were almost equal. It was found that the fatigue cracking along the deformation twin boundaries caused the reduction in fatigue life. Dislocation structure observation using the ECCI method revealed that no specific dislocation structure was formed near the cracked deformation twin boundary, although the ladder-like PSB structure was developed along an annealing twin boundary in an austenitic stainless steel.