Boldo (Peumus boldus Mol.), a Chilean tree traditionally employed in folk medicine and recognized as a herbal remedy in a number of pharmacopoeias, mainly for the treatment of liver ailments, has recently been the subject of increasing attention. Boldine, in particular, the major and most characteristic alkaloidal constituent of this plant species, now emerges as its most interesting active principle from the pharmacological viewpoint. The recent demonstration that boldine is an effective antioxidant in both biological and non-biological systems has opened up the perspective of a broad range of uses in medicine and industry. Given the toxicological data on this alkaloid, its antioxidative properties situate it as a potentially useful substance in many disease states featuring free-radical related oxidative injury. This review attempts to cover and discuss the studies conducted over the last four decades on the chemical and pharmacological properties of boldo and its main constituent.