Abstract: AIM:To compare the number of circulating smooth muscle progenitor cells (SPCs) between normal controls and patients with coronary heart disease (CHD) and to explore the influence of percutaneous coronary (PCI) on the SPC number in CHD patients. METHODS: A total of 33 hospitalized male CHD patients were enrolled and divided into three groups, including stable angina pectoris (SAP) group and unstable angina pectoris (UA) group. Patients with normal coronary angiography served as controls. The percentage of SPCs in peripheral blood mononuclear cells (PBMCs) was measured at admission and 72 h after PCI in CHD patients by double-color flow cytometry analysis. SPCs were identified with CD14+/CD105+. RESULTS: At admission, the percentage of SPCs in PBMCs was significantly higher in SAP group (0.20±0.13)% and UA group (0.28±0.18)% than in control group ［(0.12±0.10)%, all P<0.01］. The number of SPCs in UA group was significantly higher than in the SAP group (P<0.01). In the UA group, the number of SPCs at 72 h after PCI (0.34±0.25)% was significantly higher than before operation ［(0.28±0.18)%, P<0.01］ and tended to be higher than the value immediately after PCI. CONCLUSION: Stent implantation may induce the mobilization of bone marrow-derived smooth muscle progenitor cells. The number of peripheral SPCs in CHD patients is lower than in normal subjects and is negatively related with the severity of coronary heart disease. The number of circulating SPCs increases post-PCI in patients with UA.