Seeds of fruit shrubs are herbal material of relatively low popularity and a narrow range of applications. The aim of the study was to assess selected quality characteristics of the seeds of two species of flowering quince – Chaenomeles japonica cv. Nicoline and C. × superba cv. Fascinacion. Determination of the content of selected minerals showed that the seeds of C. japonica contained more potassium, iron, manganese and copper and less calcium than C. × superba. The antioxidant and antimicrobial properties of the seeds were tested in ethanol and ethanol-water extracts. For both species, the total phenolic content in the ethanol extract was statistically significantly higher than in the ethanol-water extract. This was not true of the content of antioxidants measured by the ABTS and DPPH methods. The total phenolic and antioxidant content in the seeds was much higher in C. × superba than in C. japonica. The highest phenolic content in the seeds was 51.49 mg GAE 100 g-1 DW for C. × superba and 8.63 mg GAE 100 g-1 DW for C. japonica. The total antioxidant content measured by the ABTS method in the seeds of C. japonica was 1.69 and 3.38 mmol TE 100 g-1 DW in the E and EW extracts, respectively, while in the seeds of Ch. × superba it was 18.22 and 18.78 mmol TE 100 g-1 DW. Measured by the DPPH method, it ranged from 1.76 to 11.34 mmol TE 100 g-1 DW, depending on the species. The antibacterial properties of the seeds, i.e. the susceptibility of bacterial strains to the seed extracts, were assessed by the disc diffusion method. The ability of extracts of C. × superba seeds to inhibit bacterial growth proved much greater than that of extracts of C. japonica seeds. In the case of both Chaenomeles species, the most susceptible bacteria were Enterobacter aerogenes and Enterococcus faecalis, whereas Salmonella enterica, Serratia marcescens and Escherichia coli were not susceptible to extracts of C. japonica seeds. Higher antibacterial activity against E. aerogenes and E. faecalis was observed for the ethanol extract, in which it surpassed the activity in ethanol-water extract. The study showed that the seeds of both Chaenomeles species contain valuable minerals and phytocompounds with antioxidant and antimicrobial properties.