For the detection of intrathecal immunoglobulin synthesis established methods such as the detection of oligoclonal bands, the antibody index, the IgG index and the reibergram are available. The sensitivities and specificities of these methods, however, show high discrepancies in certain diseases or are insufficient for the detection. In this work, the IgG-kappa and IgG-lambda concentrations of 99 cerebrospinal fluid samples from control, multiple sclerosis and encephalitis patients were determined by light-chain-specific antibodies. With the results of the control patients, x̅ ± 1/2/3 SD ranges (IgGk: x̅ ± SD= 14-22mg/L, x̅ ± 2SD= 10-26mg/L, x̅ ± 3SD= 6-30mg/L; IgGλ: x̅ ± SD= 11-15mg/L, x̅ ± 2SD= 9-17mg/L, x̅ ± 3SD= 7-18mg/L) and 95- (IgGк [16,6;19,6mg/L], IgGλ [12,3;13,6mg/L]) and 99% (IgGк [16,2;20,0mg/L], IgGλ [12,1;13,8mg/L]) confidence intervals were calculated as normal ranges for IgG-kappa and IgG-lambda in cerebrospinal fluid. The quantification of IgG-kappa and IgG-lambda represents a possible standard method for the detection of intrathecal immunoglobulin synthesis as well as for the diagnosis and prognosis of chronic inflammatory diseases of the central nervous system, in particular of multiple sclerosis.