This research was focused on the effectiveness of sunflower biofortification with Zn and Se towards enriched seeds, but also a side effect on the enrichment of crop residues, which can have a residual fertilizing effect. A two-year study of sunflower biofortification was conducted with foliar application of 10, 20, and 30 g/ha Se as Na-selenate or 3 and 6 kg/ha Zn as Zn sulphate in a randomized complete block design with three replications. Biofortification did not significantly affect either the seeds or the above-ground yields, but it increased the Se and Zn concentrations in seeds and vegetative mass. The Se in seeds increased 14-44 times, whereby 7.3 g/ha Se would be sufficient to achieve 300 µg/kg Se in seed. The Zn in the seed increased up to 72 mg/kg. The efficiency of biofortification in terms of Se accumulation in seeds was 15.4 – 19.3%, and Zn only 1.73 – 3.15%, which means that significant amounts of Se and Zn remain in crop residues whose incorporation into the soil has a residual effect of Zn and Se fertilization for subsequent crops.