Oligodendrocyte precursor cells (O2A/OPC, A2B5(+)) were examined for expression of neuronal nicotinic acetylcholine receptors (nAChR). RT-PCR analysis and immunocytochemistry of O2A/OPCs purified from the rat corpus collusum revealed the expression of nAChR subunits alpha3, alpha4, alpha5, alpha7, beta2, and beta4. Immunoreactivity toward nAChR subunits was not detected in cells induced to differentiate into either oligodendrocytes or astrocytes. Approximately 65% of O2A/OPCs loaded with the calcium-responsive dye FURA-2 increased their intracellular free calcium in response to nicotine application. This response was sensitive to the nAChRalpha4/beta2 antagonist, dihydro-beta-erythroidine (DHbetaE), and the voltage-gated calcium channel antagonist, nifedipine. A subset of nicotine-responsive cells (37%) established DHbetaE or nifedipine-sensitive intracellular free calcium oscillations that continued in the presence of nicotine. Typical oscillations occurred at intervals of 20 to 30 s with progressively diminished amplitudes over a period of 2 to 3 min. In rare cases, oscillations persisted for as long as 10 min. O2A/OPCs exposed to carbachol or AMPA produced no oscillations despite robust increases in intracellular free calcium. The expression of nAChRs in non-neuronal glial precursor cells suggests an expanded role for this receptor system in the development of the mammalian brain. GLIA 33:306-313, 2001. Published 2001 Wiley-Liss, Inc.