This work aimed to investigate the effect of lipoic acid (LA) on sulfane sulfur (S(*)) level and rhodanese activity in rat tissues. In vitro studies conduced so far have indicated that dihydrolipoic acid serves as an S(*) acceptor in the rhodanese-catalyzed S(*) transfer. This study revealed a significant increase in S(*) level and rhodanese activity in the heart, liver and kidney homogenates from rats that had previously been treated intraperitoneally with LA. It demonstrated for the first time in vivo that biological activity of lipoate might be connected with anaerobic cysteine metabolism to S(*) and with rhodanese activity.