Carotenoid bioactivity, namely the quenching of reactive oxygen species (ROS) and other excited-state oxidants, suggests significant clinical potential for these natural products. However, a thorough therapeutic evaluation of the carotenoids has been hampered by limited water-solubility and/or water-dispersibility ("hydrophilicity") as well as poor bioavailability. Hydrophilic carotenoid derivatives have been designed and prepared for parenteral administration. Synthetic methods, selected physical characteristics, and potential biological applications of these novel therapeutics will be discussed.