The classical theory of steroid hormone action comprises binding to an intracellular receptor followed by modulation of transcriptional and translational events. These cumbersome model explains the characteristic latency of these genomic steroid effects. Over the past two decades, increasing evidence for rapid nongenomic effects of steroids, incompatible with the traditional model, has accumulated. These alternative steroid effects have been described for all classes of steroids and a multitude of species and tissues with different mechanisms of action.