In Poland, berry fruit production occupies a very important place. Lublin region is one of the largest and most modern areas of raspberry cultivation in Poland. However, the average yields on commercial plantations are relatively low and much depended on the weather conditions. Probably, its the effect of insufficient resistance of raspberry stems and buds to freezing as well as their great susceptibility to drought and diseases. Application of Japanese biostimulator Asahi could eliminate those unfavorable factors. The preparation increases polyphenols accumulation, protecting cells and their enzymatic systems from damage it makes it possible to quickly adapt to variable; environmental conditions. The study was conducted in 1997–1999. Three raspberry cultivars were tested: Norna, Canby and Polana. The following combinations were represented: control, where shrubs were sprayed with water, and those sprayed with 0.1% Asahi solution. The treatments with Asahi were made manually twice: first – at the beginning of flowering (for green bud), second – at full of flowering. It was found that during three years Asahi increased the fruit yield by 14.7-21.2%, depending on the cultivar and by 15.4-19.9%, depending on the weather conditions. No significant effect of the preparation on fruit size was observed in all cultivars. Asahi decreased the reducing sugar content, transforming them into oligosaccharides. Besides it elevated anthocyanide level. Dry matter and vitamin C contents decreased.