We aimed at examining NFκB translocation in B lymphocytes during in vitro activation through the specific receptor for antigen using a technique convenient in most laboratories such as flow cytometry. We present here an original, convenient, and reproducible technique to study B cell activation events through NFκB translocation by means of a novel, specific flow cytometry assay. Intranuclear translocation of NFκB p65 was induced after a 45min stimulation; the highest signal was detected for a 10ng/ml stimulus compared to the unstimulated condition (P<0.05). Purified CD19 + B cells-cultured in the presence of optimal concentrations of anti-μ fragment Abs (10ng/ml) for 45min at 37 o C-induced a mean 60% (range: 45-67%) MFI- and thus, nuclear NFκB translocation-increase. We observed a one-pike profile of NFκB staining in PBMC B cells and a two-pike profile of NFκB staining in using tonsil B cells. B cells are susceptible to various dysregulations leading to minor to severe pathology (including immunoproliferative disorders). Studies of signal transduction carried out specifically in human B cells, using a novel technique gave considerable advantages: feasibility, sensitivity, reproducibility, ease.