R-type(Cα_v23) calcium channel contributes to pain sensation in peripheral sensory neurons. Six isoforms of Cα_v23 that result from combinations of presence or deletion of three inserts(insert I and insert in the II-III loop, and insert III in N-terminal regions) have been demonstrated to be present in different mammalian tissues. However, the molecular basis of Cα_v23 in trigeminal ganglion(TG) neurons is not known. In the present study, we determined which isoforms of Cα_v23 are expressed in rat TG neurons using the RT-PCR analysis. Whole tissue RT-PCR analyses revealed that only two isoforms, Cα_v23α and Cα_v23e, were present in TG neurons. From single-cell RT-PCR, we found that Cα_v23e rather than Cα_v23α was the major isoform expressed in TG neurons, and Cα_v23e was preferentially detected in small-sized neurons that express nociceptive marker, transient receptor potential vanilloid 1(TRPV1). Our results suggest that Cα_v23e in trigeminal neurons may be a potential target for the pain treatment.