Hybrid sunflower seed, regularly protected with chemicals, is used for sowing in the second or the third year if not used in the first year after production. In that case, it is stored in warehouses, and the length of storage period may significantly affect the quality of seeds. An experiment was conducted in Laboratory for Seed Testing of Institute of Field and Vegetable Crops in Novi Sad, in order to examine the effect of storage period on germination of treated sunflower seeds of three commercial hybrids of the Novi Sad Institute. The seed was treated with fungicides - metalaxyl and fludioxonil, as well as with insecticides - thiamethoxam and imidacloprid, while untreated seeds served as control. The sowing was repeated throughout the year, at three-month intervals. The obtained results indicated that, on average, the hybrid Sremac had the highest (94.61%), and the hybrid Šumadinac the lowest seed germination (90.29%). After one year of storage, seed germination declined significantly. All three hybrids treated with fungicides and the control had a significantly higher germination than hybrids treated with insecticides. This regularity was not evident right after the treatment - it became noticeable during the storage.