In the present study we describe a technique for the preparation of a highly purified B cell population from peripheral blood mononuclear cells (PBMC) by immune rosette depletion of non-B cells utilizing monoclonal antibodies directed at T cells, monocytes and null cells. The non-rosetted population contains greater than 90% B cells after a single rosetting step. The technique is simple, rapid and reproducible and results in minimal cell loss. In contrast, the E rosette negative (E-) fraction contains approximately 20% B cells whereas the surface immunoglobulin positive (sIg+ population obtained by Sephadex-anti-F(ab')2 column chromatography is comprised of approximately 60-80% B cells.