Sweet pepper is an important horticultural crop, not only because of its economic importance, but also for the nutritional value of its fruits, mainly due to the fact that they are an excellent source of natural colours, especially carotenoids, and antioxidant compounds. Sugar content in the pepper fruits is the most important component of sweet taste of these fruits. In the available literature there are not many information about the influence of biological preparations on the content of the biological compounds and nutritional value of sweet pepper fruits. The aim of this study was to estimate the influence of biological preparations (Bioczos Plynny, Biosept 33 SL, Bio-algeen S90 Plus, Boni Protect Forte) on the quantitative and qualitative composition of saccharides in the fruits of Roberta F-1 cv. in 2010-2012. The present study evaluated fructose, glucose and sucrose content in sweet pepper fruits. During the middle of the harvest period, ripe healthy and typical for cultivar fruits were collected for analysis. Sugars concentrations were determined in the water-soluble fraction, using high-performance liquid chromatography HPLC. Studies have shown that sweet pepper fruits, which plants were protected with biological preparations, were characterized by a high content of reducing sugars (glucose and fructose) and low content of sucrose. The protective using of tested biological preparations does not change significantly of saccharides content in sweet pepper fruits. However the results show that the treatment with biopreparation Boni Protect Forte resulted in a slight increase the content of glucose and fructose in pepper fruits, but the using of Bioczos Plynny decreased the content of glucose and sucrose.