For over a decade, superhydrophobic surfaces have gained significant attention within the scientific community as well as different industries because of their unique water-repellent, self-cleaning, anti-fouling, anti-icing, anti-sticking, anti-contamination properties, and their promising potential for practical applications [1]. Among polymers, polyurethane (PU) is one of the most versatile materials which is widely used in applications ranging from foams and coatings to medical devices [2]. Surface modification of PU films and coatings could be very influential on the behavior of this material for biomedical applications especially where blood compatibilitiy is concerned. Therefore, PU/Silica thin films were prepared in this work, and the main aim is to study the role of surface modification of silica nanoparticles on the wetting behavior of PU surfaces. To this end, scanning electron microscopy is also used to observe the effect of different silica nanoparticles on the surface morphology of the films. Water contact angle measurement results showed that, depending on the used nanosilica type, a diverse range of wettabilities including superhydrophobic and superhydrophilic behaviors were attained. Keywords: Polyurethane; Nanosilica; Superhydrophobic References: [1] I. Hejazi, B. Hajalizadeh, J. Seyfi, G.M.M. Sadeghi, S.H. Jafari, H.A. Khonakdar, Applied Surface Science 293 (2014) 116. [2] S.A. Madbouly, J.U. Otaigbe, Prog. Polym. Sci. 34 (2009) 1283.