Immunoglobulins are proteins produced by plasma cells and humans normally produce five different immunoglobulin classes of IgG, IgA, IgM, IgD and IgE. The basic function of the immunoglobulins is to counteract the invasion of pathogenic organisms by their antibody activity and to protect against its toxic products. The basic structure of the immunoglobulins is made up of two identical heavy chains and two light chains, kappa and lambda. In healthy subjects, normal plasma cell contents of the bone marrow are 1-3 %, in patients with multiple myeloma (MM), concentrations increase to over 90 % and are comprised of a malignant transplanted plasma cell clone. This clone of cells produces a kind of immunoglobulin that can be detected using various laboratory methods in both serum and urine. Analysis of free light immunoglobulin chains (kappa and lambda) in human serum occurs in the diagnosis and follow-up of MM and provides a simpler and faster alternative to daily urine collection for the analysis of light immunoglobulin chains in the urine. The purpose of the study was to carry out a method verification of free light chains in serum using an automated immunochemical instrument, BN Prospec II from Siemens, which uses the nephelometric measuring principle (antigen-antibody complex). The calibration concentrations of kappa and lambda assigned by Siemens were met. The method's stability and precision were measured by analyzing high and low controls for both analytes in each of the internal and total series. Within the series received CV 1,47 % for SL1 kappa and 2,57 % for SL2 kappa, and 1,77 % for SL1 lambda and 2,57 % for SL2 lambda. The total series was obtained CV 1,58 % for SL1 kappa and 2,81 % for SL2 kappa and CV 2,05 % for SL1 lambda and 2,30 % for SL2 lambda. The correctness of the method was studied through a patient comparison where 64 patient samples previously analyzed in Lund were analyzed in Kalmar. The study showed good precision and repeatability, the results of the patient comparison showed good correspondence with corresponding methods performed in Lund when the coefficient of determination for S-FLC-kappa was 0, 999 and 0, 958 for S-FLC-lambda. The conclusion is that analysis of free light chains in serum can be used in routine operation in the laboratory for clinical chemistry and transfusion medicine at the county hospital in Kalmar.