The action of androgens in many target cells is dependent on key elements such as the androgen receptor (AR) and the 5α-reductases (5αr1 and 5αr2). To get more knowledge regarding the RNA expression levels of these proteins in human skin and hair follicles, we investigated complete skin samples, single hair follicles, and hair follicle-derived keratinocytes and papilla cells. Isolated human scalp hair follicles were cultivated for up ten days in serum-free medium. Primary cell lines were established from hair follicles and from microdissected papillae by incubation in selective media. The expression levels of androgen-metabolising 5αr1 and 5αr2 and the AR were studied by semiquantitative RT-PCR. Additionally, complete skin samples were investigated. The levels of 5αr1, 5αr2, and AR-RNAs were estimated by RT-PCR with specific primer pairs followed by HPLC-quantification of the PCR-products after stimulation of cells lines and follicles with testosterone (T). Data were normalized with regard to the β-actin-RNA levels as standards. In complete skin samples and hair follicles, RNAs for both isoenzymes of h5αr and the AR were detected. In cultivated follicular keratinocytes, 5αr1-RNA was constitutively expressed and showed only minor sensitivity to T treatment. AR-RNA was downregulated by T, whereas 5αr2-RNA was induced in these cells. In papilla-cells, 5αr1-RNA was again expressed constitutively and the AR-RNA was downregulated by T. Even after stimulation with T, 5αr2-RNA was not detectable in these cells. The key enzymes of androgen action were differentialially distributed on the RNA-level in human skin and the hair follicle. Our data indicate, that androgen-dependent processes in the skin may be feeded by the locally activation of T by the isoenzymes of 5α-reductase.