Though the nicotinic acetylcholine receptor (nAChR) subunits alpha9 and alpha 10 have been thoroughly characterized within hair cells of the organ of Corti in the inner ear, prior studies have shown that they are also expressed in lymphocytes. In this report, we sought to more definitively characterize the nAChR subunits alpha9 and alpha10 within various populations of human lymphocytes. Using a combination of techniques, including RT-PCR, single-cell RT-PCR, Northern and western blot analysis, and immunofluorescence, expression of both alpha9 and alpha 10 was demonstrated in purified populations of T-cells (CD3+, CD4+, CD8+ and the Jurkat, MT2 and CEM T-cell lines) and B-cells (CD19+, CD80+ and EBV-immortalized B-cells). Single-lymphocyte recording techniques failed to identify an ionic current in response to applied acetylcholine in either T-cells or B-cells. These results clearly demonstrate the presence of these nicotinic receptor subunits within several populations of human lymphocytes, implicating their role in the immune response. However, a lack of demonstrated response to applied acetylcholine using standard single-cell recording techniques suggests a physiology different than that seen in hair cells of the inner ear.