Experiments were conducted at the Experimental Field Station of the Institute of Plant Protection – National Research Institute in Winna Góra, in 2011–2012. The aim of the study was to assess the effects of biostimulator Aminoplant on the development and yield of sugar beet and the activity of herbicides. The primary protection from weed control was treatments with a mixture of two herbicides Betanal EC 274 Elite with Safari 50 WG in three terms, in the split dose. Aminoplant applied two or three times together with herbicides and three times in a single operation. The application of Aminoplant increased the yield of sugar beet roots, but had no significant effect on the quality parameters of sugar beet roots like sugar, sodium, nitrogen and potassium content. The addition of biostimulator Aminoplant to herbicides had no negative effect on treatment efficacy and phytotoxicity against sugar beet plants. Aminoplant application date and number of treatments should be adjusted to the possibilities of chemical weed control and the appropriate growth stage of sugar beet.