This retrospective study investigated CD34, alpha-smooth muscle actin (alpha-SMA), and transforming growth factor-beta1 (TGF-beta1) expression in stromal cells of cervical intraepithelial neoplasias (CINs; n = 30), invasive cervical squamous cell carcinomas (SCCs; n = 38) and adjacent normal cervix. Normal cervix and CINs contained diffuse CD34-positive stromal cells but no alpha-SMA-positive myofibroblasts. In contrast, 34 of 38 SCCs were free of CD34-positive stromal cells and all contained alpha-SMA-positive stromal myofibroblasts; adjacent normal tissue contained CD34-positive stromal cells and no alpha-SMA-positive myofibroblasts. More intense TGF-beta1 expression was observed in SCC cells than in normal cervical epithelium or CINs. This study shows that the disappearance of CD34-positive stromal cells and appearance of alpha-SMA-positive stromal myofibroblasts may be associated with transformation of cervical CIN to SCC. These findings support the suggestion that over-production of TGF-beta1 in SCC cells is one potential mechanism mediating the transformation of stromal cells to myofibroblasts in cervical carcinogenesis.