Background: The disease-associated cell lines used in the majority of preclinical trials should be first authenticated and identified to avoid directing research expenditure on wrong cells and obtaining irrelevant results. The present study evaluated the immunophenotypic and immunotypic authenticity of six human myeloma cell lines (HMCLs). Materials and Methods: Cytospin smear and Wright staining were used for invetigating cell morphology, the flowcytometry of the markers CD45, CD2, CD19, CD38 and CD138 for immunophenotypic investigations, capillary electrophoresis for the immunoglobulin secretion potency and immunofixation for the immunotypical investigation of the cells. Results: Given the definite plasma cell morphology, the identity of all the cell lines was confirmed, although a similar morphology was observed in L363 and JJN3. In addition to authenticating the myeloma nature of all the cell lines, immunophenotypic investigations suggested a complete similarity between L363 and JJN3 cell lines. Examining their immunotypes for a final confirmation found KMS12BM to be non-secretor, KMM1 to be BJP-λ and the remaining to be IgG-λ. Conclusion: Despite confirming the identity of four cell lines, i.e. RPMI-8226, KMS-12BM, KMM1 and LP1, that of JJN3 and L363 cells, whose immunotype was determined as IgGλ, was questioned owing to their fundamental morphological, immunophenotypic and immunotypic similarities. On the other hand, a reveiew of literature and ATCC.org suggested that the main nature of JJN3 is IgAκ. The authenticity of the JJN3 cell line was therefore unclear and it was indeed the same as that of L363. The JJN3 cell-line was therefore discarded, and the associated results were interpreted as consistent with the results of L363.