Citrinin is a quinonemethine mycotoxin produced by diverse fungal genera, including Aspergillus and Penicillium. Citrinin has been extensively investigated. It is a potent nephrotoxin with hepatoxic and teratogenic activity. It is the causative agent of Balkan nephropathy and yellow rice fever in humans. At the molecular level, citrinin exhibits a range of effects including free radical damage to DNA and disruption to a wide variety of mitochrondrial membrane-bound enzymic activities and structural integrity. Specifically, citrinin is an inhibitor of NADH dehydrogenase in the mitochondrial electron transport chain and this action is responsible for recent reports of citrinin's apoptotic activity.