The proliferation of vascular smooth muscle cells (VSMC) and the increased synthesis and accumulation of extra-cellular matrix (ECM) are involved in the development of complex atherosclerotic lesions and post-angioplasty restenosis. Both of these pathological processes are under the control of different effectors or inhibitors mainly cytokines and cell growth factors. Among these factors, Platelet Derived Growth Factor (PDGF) and Transforming Growth Factor β (TGFβ) have been shown to play a major role. They stimulate VSMC proliferation and the synthesis and accumulation of ECM. On the contrary, Interferon gamma (IFNγ) has been shown to inhibit the production of ECM and to antagonize the increased production induced by PDGF or TGFβ. The studies of IFNγ on VSMC proliferation have shown contrasting results. For these reasons, we were interested to further characterize the effect of IFNγ on VSMC proliferation and on their production of gelatinase activity, a metalloprotease which is involved in the degradation of ECM.The study was performed on primary cultures of porcine VSMC derived from aorta and carotide and on a cell line derived from vein. Our results showed that PDGF and TGFβ in a less extent stimulated the proliferation of VSMC. On the opposite, IFNγ inhibited cell proliferation. This inhibition slightly decreased when higher concentrations of IFNγ were used. PDGF or TGFβ increased the production of gelatinase activity by VSMC. IFNγ alone had no effect but inhibited the increased production of gelatinase induced by PDGF or TGFβ.