Optical properties of zinc oxide nanowire (NW) dilute suspensions in polydimethylsiloxane (PDMS) were investigated. Optical transmittance was found to decrease at the transition from chaotically oriented state to electrophoretically ordered state with the alignment of the NW along the direction of incident light. Previously reported observations of the behavior of dispersions containing oblong particles indicate that the transition of the orientation of particles from chaotic to ordered state induces increase in transmittance that may be attributed to the decrease of absorption or scattering cross-section. The measurements carried out in this study on ZnO nanorod suspensions demonstrate an unexpected opposite effect – the transmittance of the suspensions decreases significantly as orientational order is induced in the suspension. The observed behavior was employed in Smart Window technologies. Smart windows are gaining interest due to the potential for increased energy efficiency in building and transport, as well as in providing privacy in office and living rooms without loss of natural illumination. We demonstrate up to 40% change of transmittance in 0.05 vol % ZnO NWs dispersed in PDMS in a simple test cell as NW alignment is induced electrophoretically. Obtained dilute NW suspensions exhibit spontaneous recovery, excellent cycling stability (0% of contrast change after more than 10 cycles) and stability against sedimentation. Overall we describe a scalable concept for a smart window device based on dilute ZnO NW suspensions in PDMS.