Electronic devices may have openings that serve as potential pathways for moisture intrusion into interior portions of the devices. An electronic device may be provided with moisture repelling coatings in the vicinity of these openings to help prevent moisture from reaching the interior of the device. The openings may be associated with gaps between adjacent housing structures, openings for buttons, openings for audio and connector ports or other openings in device structures. The moisture repelling coatings may be applied to housing surfaces, button members, structures associated with audio and connector ports, and other device structures.