In a group of 54 patients with multiple myeloma, hitherto not treated by chemotherapy, the paraprotein index was assessed. It was revealed that this simple and readily available indicator is related to the degree of anaemia, the serum beta-2-microglobulin value, the degree of bone marrow infiltration by myeloma plasmocytes and the survival period. The authors found no relation to age, albumin, urea, creatinine, serum calcium values and degree of skeletal affection. It was revealed that values of the paraprotein index declined with the advancing disease evaluated according to Durie-Salmon's system. It may be said that the paraprotein index can be considered in patients with multiple myeloma an indicator which contributes to more profound knowledge of individual biological characteristics of the myeloma population and the prognosis of the disease.