The present study comprises a kinetic comparison of the reactivity of electrochemically generated superoxide, O-2(.-), and hydroperoxyl, HO2., radicals toward a mixture of beta -carotene geometric isomers versus all-trans-retinol (vitamin A). Rate constants were determined by computer simulation of experimental cyclic voltammetric data. It is reported that all-trans-retinol reacts more readily with both O-2(.-) and HO2. than a mixture of geometric beta -carotene isomers. Specifically, the latter is unreactive at less than or equal to 25 mM with O-2(.-) within the timescale of cyclic voltammetry, while it reacts with HO2. at least an order of magnitude slower than all-trans-retinol. Our results indicate that all-trans-retinol is a better radical scavenger than a mixture of geometric beta -carotene isomers and parallel the results of a recent epidemiological study which has shown that vitamin A may be a better anticarcinogenic agent than beta -carotene.