AbstractPurpose: The appearance of the cervical mucosa is regulated by different factors including retinoic acid. Hormone-dependent alteration of the cervix uteri mucosa is accompanied by a decrease or increase of cytoplasmatic retinoic-acid-binding protein (CRABP). To elucidate whether this hormone-dependent alteration of CRABP is preserved in the case of neoplasms of the cervix uteri, we measured the level of total and apo-CRABP in normal and neoplastically transformed cervical cells. Methods: In a prospective pilot study, standardised biopsies of normal epithelium and cervical intra-epithelial neoplasm grade 3 (CIN III) were taken from 24 patients. A newly developed method was used to determine the intra-epithelial level of apo- and total CRABP. Results: The concentration of total CRABP in normal squamous epithelium compared with that in intra-epithelial neoplasm grade 3 is very significantly lower in the CIN III areas (normal: 3.661.46pmol/mg wet weightSD; CIN III 1.430.59pmol/mg P0.01). In addition CRABP in the apo form is lower in normal than in neoplastic epithelium (Wilcoxon test for paired non-parametric values: P0.05; mean for all patients: normal: 1.65+0.82pmol/mg; CIN III: 1.140.23pmol/mg). Conclusion: From our results we conclude that, in neoplastically transformed cells, the hormone-dependent CRABP cycle is interrupted. Whether this has consequences for the further development of the neoplastic cells has to be elucidated.