There have been major advances in the treatment of multiple myeloma in the past 20 years, but for the individual patient the prognosis still remains uncertain. As the length of survival varies from several months to over 10 years, definition of prognostic parameters at the time of diagnosis, and early detection of disease activity are most important. In our study, median survival was 42 months with very good quality of life. Factors not helpful in prognosis were sex, WBC and platelet counts, BUN, serum M protein type, extent of osteolytic lesions, percentage of plasma cells in bone marrow and plasma cell asynchrony. However, age, hemoglobin, calcium, uric acid, Bence-Jones proteinuria and polyclonal Ig concentrations had a certain degree of prognostic importance. Due to more sensitive and more specific laboratory methods, peripheral blood findings are lately gaining in importance. With new "salvage" protocols, the detection of additional prognostic parameters and sensitive indicators of disease activity may be most important for further improvement in the survival of patients with multiple myeloma.