Wover-fiber reinforced composites become more and more important for lightweight construction components, smart textiles and numerous other applications. The interaction between the two components of the composite depends on the chemical, physical and mechanical properties, and on the manufacturing process of the composite. To obtain a strong interaction between different polymers is problematic. Surface modification could be a solution for a more favorable adhesion between the two polymers. In this study the interphase between polyamide 6 (PA6) and polypropylene (PP) was investigated. PA films were laminated with PP or with plasma-treated PP. It was found that laminates containing plasma-treated PP show an increased shear stress compared to laminates with non-modified PP. Fourier transform infrared spectroscopy (FTIR) analysis showed a small amount of carboxylic groups on the surface of modified PP films and contact angle analysis showed a decrease of the water contact angle of PP after plasma treatment. These findings suggest a rise of the polarity of PP, which makes PP more compatible to interact with PA6. Additionally, melt rheological analysis confirmed the increased interfacial strength between PA6 and plasma-treated PP. In conclusion, plasma treatment of PP can improve the adhesive behavior between PA6 and PP.