Antibacterial and antifungal activity of ethanolic extract of grapefruit (Citrus paradisi Macf., Rutaceae) seed and pulp was examined against 20 bacterial and 10 yeast strains. The level of antimicrobial effects was established using an in vitro agar assay and standard broth dilution susceptibility test. The contents of 3.92% of total polyphenols and 0.11% of flavonoids were determined spectrometrically in crude ethanolic extract. The presence of flavanones naringin and hesperidin in the extract was confirmed by TLC analysis. Ethanolic extract exibited the strongest antimicrobial effect against Salmonella enteritidis MIC 2.06%, m/V). Other tested bacteria and yeasts were sensitive to extract concentrations ranging from 4.13% to 16.50% (m/V).Ispitano je djelovanje etanolnog ekstrakta sjemenki i pulpe ploda grejpa (Citrus paradisi Macf., Rutaceae) na 20 sojeva bakterija i 10 sojeva kvasnica. Antibakterijski i antifugalni učinak ekstrakta testiran je postupkom difuzije na hranjivom agaru i standardnom metodom dilucije. Spektrofotometrijski je određeno da suhi ekstrakt sadrži 3,92% ukupnih polifenola, dok je udio flavonoida iznosio 0,11%. Prisutnost flavonona naringina i hesperidina u etanolnom ekstraktu potvrđena je tankoslojnom kromatografijom. Ekstrakt je pokazao najsnažniji učinak na vrstu Salmonella enteritidis (MIC 2,06%, m/V), dok je na ostale ispitane bakterije i kvasnice djelovao u koncentracijama od 4,13% do 16,50% (m/V)
