Carnosol and carnosic acid are the two major polyphenolic diterpenes found in many plants. Carnosic acid has been widely investigated while there are limited reports on carnosol. The plant family Lamiaceae is the main natural source of carnosol. Though carnosol was identified more than half a century ago, its bioavailability and toxicity were rarely reported. Pharmacologically, carnosol is a potent anti-oxidant and demonstrates anti-cancer and neuroprotective effects. No clinical trial has been performed on this compound. Extracts containing carnosol have been widely studies. However, pure carnosol must be investigated in future works to elucidate its biological profiles accurately.