New insights into the molecular biology of both multiple myeloma and chronic lymphocytic leukemia can potentially lead to new treatment modalities. For myeloma, its lack of CD34 expression can lead to a functional but less contaminated autograft for stem cell transplantation. Single or even double transplants are being used to treat high-risk or even relapsed disease. Cytokines, such as interleukin-6, appear to play a role in tumor growth and bony complications as well. The bisphosphonate drugs are now known to decrease skeletal complications. For chronic lymphocytic leukemia, the nucleoside analogues have produced impressive response rates in many patients. Cell surface markers and cytogenetic abnormalities continue to identify patients with poor prognoses. Myeloablative therapy remains controversial for this disease.