The invention provides specific binding members, for example in the form of antibody variable domains, based on the CDR3 sequences of the antibody VH regions of SL15 (SEQ ID NO:4) and JT182 (SEQ ID NO:10). The antibodies have strong neutralising activity for TGF.beta..sub.1 and are useful in treating conditions associated with excess TGF.beta..sub.1 activity, such as fibrosis, immune responses and tumor progression.