The aim of this doctoral dissertation was to valorize raspberry seeds with endocarp (hereinafter: seeds) as by-products (waste) from the production ofraspberry juice and pulp. Valorization was performed through the content of high quality oil and the content of phenolic compounds with an emphasis on the content of ellagic acid. The oil from the seeds of three varieties of raspberry (Willamette, Polka and Meeker) was extracted using four extraction techniques: solid-liquid extraction (extraction with ethanol, mixture of methylene chloride/methanol and chloroform), Soxhlet extraction with hexane, supercritical carbon dioxide and cold pressing, followed by extracritical carbon dioxide extraction. Extraction methods were optimized to achieve the highest oil content. Supercritical fluid extraction was optimized by applying Box-Behnken experimental design and response surface methodology. This extraction method was specially investigated because it is a “green” extraction technique, after which the product is immediately ready for use, i.e. there is no need to evaporate the solvent, as well as because the literature review found that there is not optimization data for these methods for extracting raspberry seed oil. From the defatted seed, ellagic acid was extracted using four extraction methods, namely solid-liquid extraction with ethanol, ultrasonic, microwave and pressure solvent extraction. Extraction methods were optimized to obtain the extracts with highest ellagic acid content, and the ultrasonic extraction method was optimized using BoxBehnken experimental design and response surface methodology. Furthermore, the fatty acid composition of extracted oils was examined, where the presence of a significant amount of polyunsaturated fatty acids was determined, as well as the optimal ratios of ω–6/ω–3 fatty acids for use in human nutrition. The content of tocopherol was also examined, where the presence of significant amounts in α, γ, and δ-tocopherol was determined, while β-tocopherol was not detected in any of the samples. As for polyphenols, the content of ellagic acid in all samples was examined, as well as the phenolic profile of the extracts, where the presence of a large number of flavonols, anthocyanins and phenolic acids was determined. Then, the biological activities of the oil extracts were examined by antioxidant test on 2,2-diphenyl-1-picrylhydrazyl-radical (DPPH∙) and antimicrobial (diskdiffusion method) in vitro tests, where a significant antioxidant effect of the oil was determined, while the antimicrobial effect was not proven. The biological activity of the polyphenolic extract was examined by antioxidant (DPPH∙, ABTS∙+ and FRAP), antimicrobial (disk diffusion method) and antiproliferative (on HeLa, MCF7 and MRC-5 cell lines) in vitro tests, where a significant effect of the extracts was found in all three test. Based on the results, it can be concluded that this by-product can contribute to the functionality of the food as a supplement.