Introduction: Multiple myeloma is a malignant hematological disease that occurs as a result of uncontrolled clonal proliferation of plasma cells. It occurs most often in elderly patients and is characterized by the presence of monoclonal immunoglobulin and free light chains in serum and/or urine. Bence Jones proteins are monoclonal free immunoglobulin light chains, kappa and lambda, which are used as an important marker in the diagnosis of multiple myeloma. Laboratory diagnosis of multiple myeloma includes various laboratory tests, including serum protein electrophoresis, serum immunofixation, urine immunofixation, and measurement of serum free light chain concentration. Objective: The purpose of the study was to examine paraprotein in the serum and urine of selected patients with a referral diagnosis of multiple myeloma using different laboratory methods and techniques. Materials and methods: Serum and 24-hour urine samples of four patients with a referral diagnosis of multiple myeloma received at the Department of Medical Laboratory Diagnostics of UHC Split were selected for laboratory testing, which included serum protein electrophoresis, serum and urine immunofixation, and measurement of the concentration of free light chains in serum. Results: A suspected monoclonal peak was observed in serum protein electrophoresis for three of four patients, and using the serum immunofixation method, a monoclonal IgG kappa type protein was identified. Urine immunofixation proved the presence of Bence Jones protein in one of the four samples. An elevated concentration of free light chains was demonstrated in one of four samples, and an elevated concentration ratio of free light chains kappa/lambda was observed for two of the four samples. Conclusion: Paraprotein or M-protein was demonstrated for three out of four patients with a referral diagnosis of multiple myeloma.