A total of 55 formalin-fixed and paraffin-embedded specimens of normal, inflamed and neoplastic uterine cervix have been studied in order to correlate the epithelial changes with the expression of alpha-smooth-muscle actin in stromal cells. This actin isoform is typical of smooth-muscle cells, but appears also temporarily in fibroblasts during wound healing and permanently during fibrocontractive diseases and stromal reaction to epithelial tumors. While positive stromal cells were absent in normal and inflamed cervix, they accumulated in relation to neoplastic tissues. The number of alpha-smooth-muscle actin positive cells and the intensity of stain were related to the increasing grading of cervical intra-epithelial neoplasia. Our results suggest that alpha-smooth-muscle actin is a marker of stromal-cell reaction to the development of neoplastic lesions. The evaluation of alpha-smooth-muscle actin in stromal cells of the uterine cervix may be a useful adjunct to diagnostic criteria of cervical intra-epithelial neoplasia and may help understanding of the mechanisms of mesenchymal-epithelial interactions during neoplasia.