OBJECTIVE: To observe the effect and the mechanism of Chrysanthemum morifolium Ramat on apoptosis of bovine aortic smooth muscle cells. METHODS: Vascular smooth muscle cells were isolated from thoracic aorta of fetal calf and cultured, then incubated with different concentration of Chrysanthemum morifolium Ramat. Apoptosis was measured by flow cytometry. SOD and MDA were measured by spectrophotometer. RESULTS: We found that: (1) the number of apoptotic cells was reduced from (4.425+/-0.624)% to (2.875+/-0.640)% in Chrysanthemum morifolium Ramat group, in a concentration dependent manner; (2) the value of SOD was increased from (1.683+/-0.149)X10(4) U/L to (2.297+/-0.230)X104 U/L and the value of MDA was reduced from(166.454+/-56.805)&mgr;mol/L to (73.068+/-27.203)&mgr;mol/L in Chrysanthemum morifolium Ramat group, also in a concentration dependent manner. CONCLUSION: Chrysanthemum morifolium Ramat can inhibit apoptosis of vascular smooth muscle cells in a concentration-dependent manner.