The effect of the presenting clinical features on survival time was evaluated in 173 patients of a population of 201 individuals with multiple myeloma observed at Malmo General Hospital during the 11-yr period 1960 to January 1, 1971. Complete follow-up was continued until December 1978. One-hundred and five of the patients came from the city of Malmo and constitute a complete nonselected myeloma population. Bivariate correlation and multivariate regression analyses showed that the survival (i.e., the prognosis) could be accurately predicted in IgG and pure Bence Jones myeloma patients from (A) serum creatinine level, (B) serum calcium level, and (C) bone marrow plasma cell percentage; and in IgA myeloma patients from (A) hemoglobin level, (B) serum calcium level, and (C) serum M-component level. The results were synthesized to produce a simple and reliable clinical staging system with three stages (i.e., risks of death). To facilitate the clinical application, multivariate regression equations were developed to optimally predict the prognosis, and graphs were constructed in order to make the staging of the myeloma patients easier and quicker. The comparison of the duration of survival between the three groups of staged patients confirmed the high reliability of the present staging system.