1. Introduction. -The biological effects, biodistribution, pharmacological activity, and toxicology of vanadium are areas of increasing research interest. Although numerous biochemical and physiological functions have been suggested for this element, and despite the amount of the knowledge so far accumulated, vanadium still does not have a clearly defined role in the higher forms of life [1 -5].So far, the best evidence for a biological role of vanadium comes from bacteria (the so-called alternative nitrogenases in which vanadium replaces molybdenum in the FeMo-cofactor of some Azotobacter species) [ Environmental contamination by vanadium has dramatically increased during the last decades, especially in the most developed countries, due to the widespread use of fossil fuels, many of which liberate finely particulate V 2 O 5 to the atmosphere during combustion [13 -15]. Therefore, and also owing to the emerging interest in the pharmacological effects of some of its compounds [16 -20], the toxicology and detoxification of vanadium constitute areas of increasing research interest. The older literature about vanadium toxicology has been reviewed in the classical work of Faulkner-Hudson [21], and we have analyzed the most relevant aspects of its detoxification some years ago [22]. The pertinent information is extended and updated in the present review.Vanadium toxicity has been reported in experimental animals and in humans. The degree of toxicity depends on the route of incorporation, valence, and chemical form of the element, and is also, to some extent, species-dependent [21] [22]. In general, it increases as valence increases, pentavalent vanadium being the most toxic [22] [23]. Although, under normal natural conditions, toxic effects do not occur frequently, at high doses or as a consequence of chronic exposure, it is a relatively toxic element for humans [24].The upper respiratory tract is the main target in occupational exposure. Vanadium compounds, especially V 2 O 5 , are strong irritants of the airways and eyes. Acute and