A field experiment was conducted at the Agronomy Department Experimental Farm, Agriculture Faculty, Assiut University, Egypt. During 2015/2016 and 2016/2017 seasons to study the effect of yeast rates and potassium fertilization on yield and quality of some sugar beet varieties. The experiment was laid out in randomized complete block design (RCBD) using strip split plot arrangement with three replications. Yeast foliar application rates (0,1,2 and 3 kg fed. ^-1) was arranged horizontally, while potassium fertilization levels (12.5, 25 and 37.5 kg K₂O fed.^-1) were distributed in vertically, as well as sugar beet varieties (kawemira, Romulus and Glorius) were arranged in sub plots. The obtained results revealed that yeast foliar application at the rate of 3.0 kg wet yeast fed.^-1 recorded the highest significant mean values of root length, root diameter, single root weight, root yield fed.^-1, pol percentage, sugar recovery percentage and recoverable sugar yield (ton fed.^-1) traits in the two growing seasons. Furthermore, the obtained results detected that the studied potassium fertilization levels had a significant effect in the all studied traits in the two growing seasons in favor of 37.5 kg K₂O fed.^-1. Here too, kawemira sugar beet variety gave the highest mean values of previous traits in both seasons. In addition, the obtained results revealed that the all first and second order interactions involved in this respect had a significant influence on all studied traits. Moreover, kawemira sugar beet variety which sprayed with 3 kg yeast fed.^-1 and fertilized with 37.5 kg K₂O fed.^-1 produced the maximum mean values of all studied traits in both seasons.