The aim of the present study was to verify whether the modifications of the extracellular matrix, described in varicose veins, are also present in cultures of smooth muscle cells from human varicose veins. The accumulation of collagen type III and fibronectin was determined by immunofluorescence in cultures of smooth muscle cells at passage 2–3 during the proliferation phase. After 5 days of culture, the immunostaining of both collagen type III and fibronectin was weaker in cells from varicose than in those of control veins while the expression of collagen type III and fibronectin messenger ribonucleic acids was not significantly different. Collagen type I and III synthesis were quantified by tritiated proline incorporation in control and varicose cell layers at postconfluence. Collagen type I deposition was similar in both types of cell layers while collagen type III was decreased in cell layers from varicose veins. Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) were also quantified by enzyme immunoassays in supernatants from smooth muscle cell cultures at postconfluence. No significant difference was observed in the synthesis of any of the MMPs (–1, –2 and –9) or their inhibitors (–1 and –2) tested. These data illustrate that smooth muscle cells cultured from varicose veins deposit less collagen type III and fibronectin than control cells despite comparable levels of mRNAs for these proteins suggesting dysregulation of posttranslational steps in the synthesis of both proteins by smooth muscle cells from varicose veins.