RS exerts a range of beneficial effects on human health. Therefore, ways to increase the RS content in processed food products are looked for. The effects of high hydrostatic pressure treatments on the RS content of wheat, quinoa and amaranth starch were analysed in this study. A 23 factorial screening design of experiments was used. Experimental factors were pressure (100–600 MPa), temperature (40–60°C) and time (10–30 min). RS in wheat starch increased with increasing pressure by a factor of up to 10 to a value of 4%. In detail, RS content increased significantly at pressures higher than 100 MPa in wheat starch, whereas in quinoa starch significant changes occurred at pressures above 350 MPa (up to 3.3% RS compared to 0.2% in native quinoa starch). Contrary, in amaranth starch the RS content of all pressure treated samples (about 0.5%) was lower than that of the native starch (1.3%). Wheat starch granules swelled to a maximum of 3.67 times their original size and quinoa starch up to 3.36 times. The extent of swelling (2.90) was lowest in amaranth starch.