Although winter rye is known for its high tolerance to biotic stress factors, several diseases are occurring in most rye-growing countries: snow mold, brown foot rot, powdery mildew, leaf rust, stem rust, Fusarium head blight, and ergot. For hybrid breeding, resistance selection is important due to the restricted genetic variation within a cultivar. For powdery mildew and the two rusts, race-specific qualitative resistances based on single resistance (R) genes and quantitative resistances have been described. For the other diseases only quantitative resistances can be selected. This chapter describes the features of snow mold, foot rot, powdery mildew, leaf rust, stem rust, Fusarium head blight and ergot. The chapter examines and assesses strategies for resistance selection and looks ahead to future trends in this area.