['Keloids are benign dermal tumors characterized by fibroblastic proliferation and excessive accumulation of collagen. Oxymatrine (OMT) is an alkaloid extracted from the Chinese herb Sophora japonica with capacities of anti-fibrosis.', 'To evaluate the effects of OMT on collagen production and to explore its mechanisms.', 'OMT was applied to human keloid fibroblasts in vitro. Collagen, transforming growth factor (TGF)-β1, TGF-β receptor, and Smads were analyzed by Western Blot, reverse transcription polymerase chain reaction, and immunofluorescence.', 'We found that both collagen synthesis and Smad3 production were significantly suppressed in a dose-dependent administration of OMT. However, expression of TGF-β1, TGF-β receptor1, TGF-β receptor2, Smad4, and Smad7 was unchanged. We also found that OMT reversed phosphorylation and nuclear translocation of Smad3 induced by TGF-β1.'] Does oxymatrine inhibit collagen synthesis in keloid fibroblasts via inhibition of transforming growth factor-β1/Smad signaling pathway?