Aim To ascertain whether Dimethylsulfoxide (DMSO)-soluble particles from cigarette smoke (DSP) stimulate the proliferation of vascular smooth muscle cells (VSMC). Methods Rabbit aortic vascular smooth muscle cells were used as target cell. The proliferation of VSMC was assayed by the measurement of MTT and flow cytometry. Cellular protein assay (ELISA) was used to observe the change of protein content. The amount of endothelin-1 (ET-1) secreted by VSMC was measured by radioimmunoassay (RIA). Results In contrast to the control group (without DSP), protein absorbance of VAMC added 1∶1000, 2∶1000 and 3∶1000 DSP did not make significant difference (p>0.05). VSMC added 1∶1000 and 2∶1000 DSP showed proliferation significantly (p<0.01), and yet 3∶1000 DSP group did not. The amount of ET-1 in the medium of DSP groups were significantly increased, especially in 2∶1000 DSP group (p<0.01) and the result of flow cytometry showed that in 2∶1000 DSP group, the cell numbers of G 1 phase were decreased and cell numbers of S phase were increased markedly (p<0.01). Conclusion 1∶1000 and 2∶1000 DSP can stimulate significantly the proliferation of VSMC, and ET-1 produced by VSMC may play an important role in the proliferation of VSMC.