The aim of the study was to determine the content of flavan-3-ols of selected fruit seeds. The investigated seeds have a very different level of flavan-3-ols and polymeric procyanidins. Seeds rowanberry and hawthorn contained the highest quantity flavan-3-ols (517.48 and 221.49 mg/100 g). However elderberry (24.15 mg/100 g) and quince (16.12 mg/100g) contained the lowest amount of flavan-3-ols. In other seed, buckthorn was measured 95.27 mg/100 g of monomeric catechin, but in flowering quince and rosehip have 165.25 and 168.37 mg/100 g. (-)-Epicatechin was dominated in seeds from flowering quince, quince, rowanberry and elderberry. The content of (-)-epicatechin in rowanberry was 460.10 mg/100 g, what was about 89% for total content of flavan-3-ols. However (+)-catechin predominated in seeds of roseship (96%). Buckthorn seeds are claimed to be rich in a complex mixture of catechins, ranging from (-)-epicatechin (54%) and (+)-catechin (46%). The contents sum of proanthocyanidins in investigated seeds ranged from 219.16 to 4263.67 mg/100 g. The lowest content of proanthocyanidins was obtained for elderberry, roseship C and B. The investigated seeds, especially rowanberry and hawthorn have excellent sources of flavan-3-ols. This result suggests that the berry seeds should be further utilized rather than just discarded as waste.