Chronic blood malignancies in the elderly remain incurable diseases. However, recent advances in therapies allow not only to extend treatment at advanced ages and in presence of significant comorbidities, but also to induce prolonged remissions. However, this is achieved at the cost of increased risk of infectious diseases, due to disease--and treatment-related immunosuppression. This article will review the infectious diseases associated with chronic lymphatic leukemia, myelodysplastic syndrome and multiple myeloma. Furthermore we will discuss the recommendation of anti-infectious prophylaxis and vaccination for each of the conditions listed above.