MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression through imperfect base pairing with the 3' untranslated region (3'UTR) of target mRNA. We Studied the regulation of alpha 1 (1) collagen (Col1A1) expression by miRNAs in human stellate cells. which are involved in liver fibrogenesis. Among miR-29b, -143, and -218, whose expressions were altered in response to transforming growth factor-beta 1 or interferon-alpha stimulation, miR-29b was the most effective Suppressor of type I collagen at the mRNA and protein level via its direct binding to Col1A1 3'UTR miR-29b also had an effect on SP1 expression These results suggested that miR-29b is involved in the regulation of type I collagen expression by interferon-alpha in hepatic stellate cells. It is anticipated that miR-29b will be used for the regulation of stellate cell activation and lead to antifibrotic therapy (C) 2009 Elsevier Inc All rights reserved.