The NF-kappa B transcription factor modulates a number of gene responses to hormonal stimuli. NF-kappa B can be induced by growth promoting hormones and cytokines, has been shown to counteract the effectiveness of steroid hormones and has recently been found to be regulated during mammalian spermatogenesis. Recent advances in the characterization of the NF-kappa B signaling pathway offer new opportunities to examine how hormonal stimuli regulate NF-kappa B mediated gene expression. In this mini-review we outline the signal pathways responsible for activating NF-kappa B, discuss the hormonal regulation of NF-kappa B and the regulation of hormonal responses by NF-kappa B, as well as summarize new studies characterizing NF-kappa B expression and activity in the mammalian testis. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.