Tamoxifen is important therapy for postmenopausal patients with breast cancer. Whilst effects are largely mediated via the oestrogen receptor (ER), the growth suppressive effects of transforming growth factor betas (TGFβs) may also be involved. Expression of the isoforms of TGFβ mRNA has been measured by RNAase protection assay in 37 breast cancer patients treated with tamoxifen. All tumours expressed the isoforms both before and after treatment, and semi-quantitative assessment showed no consistent changes in TGFβ1, or β3 in either responding or non-responding patients. However, there was a significant trend for responding patients to show increasing TGFβ2 expression (11/27) as compared to only 2/10 non-responding patients (p = 0.018), The present study suggests that response to tamoxifen may be associated with an increase in expression of TGFβ2 mRNA in a proportion of breast cancers. Tamoxifen is important therapy for postmenopausal patients with breast cancer. Whilst effects are largely mediated via the oestrogen receptor (ER), the growth suppressive effects of transforming growth factor betas (TGFβs) may also be involved. Expression of the isoforms of TGFβ mRNA has been measured by RNAase protection assay in 37 breast cancer patients treated with tamoxifen. All tumours expressed the isoforms both before and after treatment, and semi-quantitative assessment showed no consistent changes in TGFβ1, or β3 in either responding or non-responding patients. However, there was a significant trend for responding patients to show increasing TGFβ2 expression (11/27) as compared to only 2/10 non-responding patients (p = 0.018), The present study suggests that response to tamoxifen may be associated with an increase in expression of TGFβ2 mRNA in a proportion of breast cancers.