Serum beta 2-microglobulin, serum thymidine kinase, and commonly used prognostic parameters were investigated for their prognostic value in a well-defined group of patients with multiple myeloma (n = 207). Multivariate analysis showed hemoglobin to be the parameter of strongest prognostic value. Only albumin, serum beta 2-microglobulin and serum thymidine kinase added further prognostic information. When tested for efficiency in recognizing patients with poor (average survival time < 1 year) and good (average survival time > 5 years) prognosis, serum beta 2-microglobulin was best (80%), followed by total urinary protein (78%), hemoglobin (76%), and albumin (75%).