Abstract: Objective: To observe primary cilia in periodontal tissue and human periodontal ligament cells (hPDLCs) cultured in vitro. Methods: The ligaments of human and mouse were cut from the middle of roots and made into frozen and paraffin section respectively. hPDLCs were cultured in vitro. Then acet-α-tubulin antibody was used to detect the primary cilia of periodontal tissue and cells. Results: The signal of primary cilia was short rod near to the nuclei in periodontal ligament and primary hPDLCs. The length of most primary cilia was about 2-3 μm. Conclusion: Both periodontal ligament and primary hPDLCs have the primary cilia.