Structure, mechanism of action and biological role of steroidogenic factor-1 (SF-1), in particu- lar the significance of this factor for the normal function of the adrenal cortex, have been presented. SF-1 is a transcription factor, classified to an orphan nuclear receptor family, which interacts with the specific nucleotide sequence within promoters of the target genes, including those encoding proteins participating in the synthesis or transport of steroid hormones or their precursors in the cell.