In 152 patients treated with cytostatic agents for multiple myeloma the prognostic value of seven staging systems was evaluated: Carbone et al. Acute Leukemia Group B, Southeastern Cancer Study Group, Durie and Salmon, Alexanian, Merlini et al., British Medical Research Council. The staging systems of the ALGB and SECSG, both dividing patients into "good risk"- and "poor risk"-groups gave significantly different survival curves. Nevertheless, the differences were rather small. In the systems of Carbone et al., Merlini et al., Alexanian, and Durie and Salmon some of the differences in the survival curves were statistically significant while others were not. Our data best fitted into the British Medical Research Council staging system, the survival curves of all three stages showing significant differences with median survival time dropping from 83 months in stage A to 52 months in stage B and 26 months in stage C. Nevertheless, none of those systems was clearly superior to single risk factors especially creatinine and hemoglobin.