While resorcylic acid lactones (RALs) have been known for a long time, the more recent discoveries that radicicol is a potent and selective HSP90 inhibitor while other members such as hypothemycin, LL-Z1640-2 and LL-783,277 are potent kinase inhibitors have stimulated a renewed interest in this family of natural products. The recent developments regarding the chemistry and biology of RALs are reviewed.