In this paper we report the experimental results that polymer micro-emulsions (up to 10 wt%) behave like Newtonian liquids in ultrasound-modulated two-fluid (UMTF) atomization. Specifically, the emulsion drops generated are much smaller and more narrowly sized than those generated in conventional ultrasonic atomization (without air). After spray drying, the PMMA emulsion drops yield uniform nanoparticles that were originally dispersed in the micro-emulsion. Contrary to the conventional view that viscoelastic liquids are more difficult to atomize than Newtonian liquids, we found that ultrasound enhanced atomization of viscoelastic liquids such as gel-forming xanthan gum solutions. Under similar aerodynamic conditions using UMTF atomization at 54 kHz, 40-μm-diameter uniform drops were obtained for Xan solutions, but not for Newtonian aqueous glycerol of same viscosity.