The polarographic reduction of tin gives rise to an additional peak at more positive potentials than tin in the presence of selenite. It is found that when the selenite concentration exceeded the tin concentration, only one peak for tin was observed, enabling the determination of both these ions. A procedure for the direct determination of trace amounts of tin by the addition of selenite is described. It was possible to determine trace amounts of tin and selenium using this peak. Tin and selenium in a synthetic sample at 5 x 10(-6) M Sn(LT) and 2.5 x 10(-6) M Se(IV) concentrations could be determined with -6.0% and -8.0% relative errors, respectively. This procedure was applied to canned corn, and 5.95 +/- 0.54 mug/g tin could be determined with a 9.1% relative standard deviation.