The primary constituents of different rechargeable battery chemistries vary with respect to their toxicological properties, some posing significant health risks under short-term (acute) or long-term (chronic) exposure conditions. Opportunities for consumer exposure to the internal constituents of batteries are negligible under normal patterns of use. Rather, opportunities for exposure are predominantly present in the occupational setting during the manufacturing or recycling/end-of-life disposal of batteries. Toxicological properties of the principal metallic constituents of different battery chemistries are reviewed, and notations made, where appropriate, of the control technologies and occupational exposure limits that have been adopted to minimize the health impacts of occupational exposures. Battery electrolyte materials can also pose risks and some of these are briefly summarized. Finally, as a function of specific manufacturing process and proprietary technologies, some minor constituents can be present that pose unusual risk if appropriate hygiene and process controls are not observed. Examples are provided of unusual risks that can be associated with such substances.