Urania (R) flexographic printing ink was modified with the commercially available hyperbranched polymer Boltorn H2004. The surface tension of the printing inks was measured and the rheology behaviour of the printing inks was assessed. The flow curves (shear stress vs. shear rate) for the printing inks exhibited pseudoplastic behaviour. Modified flexographic inks were laboratory printed on three different plastic films: polyethylene, polypropylene and polyethylene terephthalate. The impact of a small amount of hyperbranched polymer on printing ink colour was examined by optical density, total colour difference Delta E* (CIE L*, a*, b*) and the gloss of the printed film. In general, the addition of the hyperbranched polymer improved the colour fastness and hardness resistance. The influence of the hyperbranched polymer on the rheological properties, optical density, CIE LAB coordinates and colour fastness is discussed.