OBJECTIVE: Abnormal connective tissue proliferation in muscle following muscle fibre degeneration-regeneration is a feature of muscular dystrophy. Tissue inhibitors of metalloproteinases (TIMPs) are multifunctional proteins that can modify cellular activities and modulate matrix turnover. Transforming growth factor-β1 (TGF-β1) can promote tissue fibrosis. This paper studied the role of TIMP-1 and TGF-β1 in the pathogenesis of various muscular dystrophies. METHODS: Plasma TIMP-1 and TGF-β1 levels were measured by ELISA in patients with various muscular dystrophies. Forty-one patients with non-muscle disorders were used as the Control group. RESULTS: The plasma TIMP-1 level was significantly elevated in patients with Duchenne muscular dystrophy (DMD, 122.52± 63.87 ng/ml) (P< 0.05) and congenital muscular dystrophy (CMD, 124.87± 63.14 ng/ml) (P< 0.05) when compared with that of the Control group ( 85.71± 29.13 ng/ml). Patients with Becker muscular dystrophy (BMD) had no significant elevation of the TIMP-1 level compared with the Control group. Compared with the Control group ( 6.24± 1.12 ng/ml), the plasma TGF-β1 level was significantly elevated in patients with DMD ( 26.26± 5.79 ng/ml) (P< 0.01) and CMD ( 31.35± 9.77 ng/ml) (P< 0.05), but not in patients with BMD ( 3.46± 1.38 ng/ml). There was a correlation between the concentrations of TIMP-1 and TGF-β1 (r= 0.6350,P< 0.01). CONCLUSIONS: The plasma TIMP-1 and TGF-β1 levels were elevated in patients with DMD or CMD. This elevation suggests that TIMP-1 and TGF-β1 are correlated with the clinical severity of muscular dystrophy and suggests that they may play a role in the genesis of muscular dystrophy.[WT5"H