The aim of this study was to evaluate the effects of advanced glycation end-products (AGEs) on the proliferative activity and fibronectin production of smooth muscle cells (SMCs). AGE-bovine serum albumin (AGE-BSA) was prepared by incubation with D-glucose at 37°C for 60 days. Cultured SMCs were obtained from explants isolated from porcine abdominal aorta and used between passages 3 and 10. The proliferative activity of SMCs was examined by MTT (3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyl tetrazolium bromide) assay and by incorporation of ³H-thymidine into DNA. Fibronectin production was assessed by competitive ELISA assay for both fibronectin secreted into the culture medium (M-FN) and cell-associated fibronectin (C-FN), i.e., both intra- and peri-cellular fibronectin. The MTT assay revealed that AGE-BSA did not produce any change in optical density (A₅₇₀) of SMCs at concentrations of up to 20 μg/ml, but decreased that of SMCs at a concentration of 40μg/ml. The addition of PDGF (5 ng/ml) induced an increase in ³H-thymidine incorporation into DNA of quiescent SMCs, while the addition of AGE-BSA (20 μg/ml) had no effect. In contrast, AGE-BSA significantly increased C-FN of SMCs (30.8±8.58 ng/μg TP), compared to unmodified BSA (16.5+4.19 ng/μg TP). However, no difference in M-FN levels was observed between cells treated with AGE-BSA and unmodified BSA. The addition of anti-transforming growth factor (TGF) -β antibody restored the levels of C-FN in SMCs cultured in 20 μg/ml of AGE-BSA, suggesting that TGF-β might act as an intermediate factor in AGE-induced fibronectin production by SMCs. Our results suggest that interaction of AGE-modified proteins with SMCs may play a role in the development of atherosclerosis in diabetic and non-diabetic patients.