Transforming growth factor beta (TGFbeta) immunoreactivity was determined in endometria from non-drug-therapy and tamoxifen-treated patients. Sections were scored for pathology and quantity image analysis performed to determine levels of glandular- or fibrosis-associated TGFbeta1. Tamoxifen-treated patients displayed greater levels of endometrial dysplasia and glandular hyperplasia, in addition to a statistically significant (P<0.0001) elevation in gland-associated TGFbeta1 protein.