Wool, wool/polyester and polyester fabrics are printed with rhubarb natural dye. The dried plant ismilled after which it is exposed to ultrasound waves (for a specific period of time). Both wool andwool/polyester fabrics are mordanted via padding in tartaric acid and potassium dichromate separately, priorto printing process. Dye nanoparticles are incorporated with urea in printing pastes at an acidic pH value andeventually the prints are steamed and washed off. All factors and measurements that are found to affect colouryield as well as fastness levels of the prints are investigated in detail. Results show that, printing with rhubarbnanoscaled particles enhances K/S values as well as fastness properties of the prints. SEM, FT-IR and UVvisible spectroscopes are employed to show dye-particle changes after milling as well as sonication.